Everything About Hydroponics

A Step Forward : Moving from AllHydroponics to ScienceinHydroponics.com

2010-09-21T05:09:00.001-07:00

Through the past few weeks I have been meditating about the current limitations of the blogger platform and how it makes my writing and customization options smaller and the look of my blog less professional. Due to the fact that I intend to start writing more and expanding this blog it becomes evident that I will need a much more powerful blog hosting platform and blogger seems to be limiting instead of helping my efforts in this regards. For this reason I have taken the decision to move my blog from its current blogspot home to a new self-hosted domain which I will use from now on to post new articles and releases of hydrobuddy.

This new website – scienceinhydroponics.com – will be the new home of my blogging effort in the area of hydroponic crop production and research. I will stop posting new articles on blogger and the old blogger website will start redirecting to the new wordpress based blog today. The idea of this new blog is to allow me to customize my website as much as I want and to be able to exploit the full potential of my web presence through the use of a self-hosted domain. In the future I hope that this move forward will make my content more professional and my efforts more worth-while. Future versions of hydrobuddy will now be released and maintained on the new wordpress blog and the previous blogger implementation will not be maintained anymore.

Of course if you have linked to my old blog the pages will not be deleted but they will cause automatic redirection towards my new domain. However the RSS feed will stop being updated so feel free to subscribe through my new blog’s RSS feed (links available on the top right corner of the blog). There are also now several buttons you can use in the bottom of each page to share the contents of the posts on facebook, twitter, etc and a Printer friendly function that will allow you to easily print my blog’s contents without any of the menus, etc. I hope that you will greatly enjoy this new blog which is a milestone achievement for me and the start of a new era for me as a much more professional blogger :o)

Making Isotonic Solutions For Draining : Preparing Your Own - and better - Clearex

2010-09-11T04:18:00.001-07:00

When growing hydroponic products it is common in the industry to do a final treatment before picking up the crop in which nutrients are removed from the hydroponic solutions. While in most cases this is achieved by passing RO water through the system it is true that passing water with a very low osmotic pressure can make the plants absorb larger amounts of water than what we would ideally want, disturbing the osmotic equilibrium established by the roots with the nutrient solution. An approach that has been used to solve this problem is the use of isotonic cleaning solutions - such as Clearex - which drain the hydroponic media from nutrients without subjecting the roots to the stress of an hypo-tonic solution (such as RO or distilled water).

On today's article I will teach you what the Clearex solution is supposed to achieve and how you can make your own (or even a better) solution to solve this final draining problem. First of all, removing nutrient from a hydroponic solutions is not so hard. Simply by running RO water through your system after draining the original solution you will remove most nutrients since these salts - contrary to what some companies tell you - are readily soluble and easily leave the media and roots when washed with RO water. The small problem when using RO water is that it is hypo-tonic with the roots, meaning that water will go into the roots to attempt to "lower" the concentration of the solutes within the plant's cells.
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Depending on what you want to achieve with this final draining solution you may have a problem when using such an hypo-tonic solution. In crops where there is fruit production, using such a solution can cause problems such as the rupture of fruits' skin due to the higher rate of water absorption that takes place when plants are placed in a hypo-tonic media. In order to avoid these problems the best thing is to use an isotonic solution which has an osmotic pressure similar to the original nutrient solution.

Clearex achieves this simply by combining a few sugars to a concentration of about 4-6% in order to get to the point where the osmotic pressure of both solutions is similar. Getting regular table sugar an dissolving it in a ratio of 50g per liter of solution will achieve very similar results as those obtained with Clearex. However using sugars like this can have additional problems since sugars stimulate the development of fungi and bacteria within the root zones of the hydroponic plants.

In my opinion it would be possible to achieve better results by using an isotonic solution with a combination of salts and sugars in such a way that non-nutrient salts are used to provide an ionic content to the draining solution. Using a combination of NaCl, Sucrose and Sodium Hydrogen Carbonate to achieve a more balanced solution may provide better results when doing this type of draining procedures. Of course, this is based purely on my anecdotal evidence and an adequately controlled study would be needed to say anything conclusive for a particular plant specie.

In the end making these solutions is extremely simple and buying Clearex or such other solutions made for this purpose is an obvious waste of money. If you have obtained good results with solutions like these then you can simply make your own with simple sugars while it is possible that you could obtain results just as good as those by using RO water if your crop is not sensitive to hypo-tonic conditions. If you want to experiment a bit I would recommend using a solution with about 150 mg/L NaCl, 100 mg/L NaHCO3 (sodium bicarbonate) and 10g/L of glucose. Let me know if you get better, worse or similar results :o) (note that this is NOT a straight solution but a concentrated additive that should be used until the desired EC levels are reached)

Imitating Commercial Nutrients : A Tutorial Using HydroBuddy (my free Hydroponic Nutrient Calculator)

2010-09-08T20:36:00.000-07:00

A few months after the first official release of my free hydroponic nutrient calculator it seems that many people are using it to imitate commercial hydroponic fertilizer formulations. Although the calculator had the capacity to do this from the time when the "salts to formulations" feature was implemented many users apparently did not know how to use this very well and the process seemed to be more extensive than what would be ideally necessary to get the end ppm concentration values of some commercial fertilizer formulations. In order to make the process far easier I decided to implement a new feature within the calculator that allows anyone to easily input the guaranteed analysis of any commercial fertilizer, the density, the amount of mL or grams added per Liter or gallon and get the end ppm values which can now be used as a recipe in order to come up with a personal formulation that exactly mimics this end result.
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This new feature - as shown above- is accessible through a button in the "Desired Formulation" tab. This button is located between the water quality and instrument precision buttons, just below the "preparation type" dialogue box. When this button is clicked a new window pops up in which the user can input the percentage composition of the commercial fertilizer he/she wishes to imitate as well as the manner in which this commercial fertilizer is supposed to be added in order to arrive at the final concentrations intended by the manufacturer.

For liquid fertilizers the maker usually gives you a volume measure to add per gallon or liter which should be expressed as mL per gallon or liter (you can choose if you want to specify the quantity added per gallon or liter using the radio buttons for this purpose). In the case of solid fertilizers the label usually tells you to add a given number of grams or ounces per liter or gallon. You can choose between specifying a given volume and density or a given weight by using the "Addition as weight" or "Addition as volume" radio buttons located at the top right of the new window.

Once you input these parameters you are now ready to get the intended end result for this commercial fertilizer by using the "Calculate Formulation" button. When you click this button the program will automatically calculate the end concentrations which result from adding the amount of the commercial nutrients you specified with the composition you also specified. These values are automatically copied to the "Desired Final Formulation" column and they can now be used to imitate the commercial formulation. You can now select a given number of salts you have available and use the regular preparation types in order to come up with a direct addition or 1:100 concentrated solution which will match up the end concentration results achieved with the commercial fertilizer you input.
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Of course, this will NOT guarantee a perfect copy of the commercial fertilizer since many of the ingredients a commercial fertilizer may contain may not be listed or they can be listed but their actual concentration levels may not be specified. For example you will find that many commercial nutrients contain Boron but their guaranteed analysis does not show it. This is mainly because the law does not require them to include boron in their analysis and therefore they will add it but they will not disclose its actual concentration or sometimes even its presence. Several other additives or nutrients may receive similar treatment so for this reason it is always good to make up A and B concentrated solutions or direct additions which include ALL elements necessary for plant growth.

Do you find this feature useful ? Is there any feature that you would like to see implemented in hydrobuddy ? Feel free to leave a comment with any opinion or suggestion you may have :o)

Bulding a World Without Hunger : The Massive and Passive Hydroponic System Project

2010-09-01T08:59:00.000-07:00

If you have visited my blog within the past few days you have probably realized that I am interested in the further development and use of non-recirculating, totally passive hydroponic systems which are extremely easy to use and require no electricity or high setup costs. These systems are very important due to the fact that if made cheap and reliable enough they could vastly reduce the costs and water usage of agricultural crops around the world, making food cheaper, much more widely available, giving people in third world countries independence over the conditions of their soil allowing the cultivation of a wide variety of crops in areas where it was previously simply not possible.

However the fact is that currently the knowledge we posses about totally passive systems and the reliability of such implementations (and more importantly their robustness) has not been studied widely enough. For this reason I decided to start a project called the Massive and Passive Hydroponic Project or MPHP which is my attempt to use the internet - and most importantly the people who are interested in hydroponic around the world - to research this topic and get experimental results over different parts of the world, with different conditions and with totally different plant species.
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Certainly many people will think that the information obtained in this way will have a ton of variability and therefore little value to further research on this field. On the contrary, I believe that - although such variability does exist - it could bring us very important and relevant information regarding the robustness and implementation easiness of such systems all around the world. Surely if these type of systems are to become good enough to replace a significant part of an agricultural setup they will need to be very robust and adapted against a wide variety of different conditions. This is what I want to find out with this project.

So if you want to help the world, help us gather information and build your own totally passive hydroponic crop, feel free to participate in the MPHP so that you can help us establish the robustness, production and conditions under which totally passive hydroponic systems can be implemented with success. If you want to participate just download the below mentioned document and send me an email to dfernandezp(at)unal.edu.co or leave a comment on this post. By following the instructions within the pdf and gathering information you will help build a better world and you will definitely learn a lot about passive hydroponic gardening :o)
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Completely Passive, Non-Recirculating Hydroponic Systems : Some Tips for Large Plants

2010-08-25T04:39:00.000-07:00

On yesterday's post I talked about the existence of completely passive, non-recirculating hydroponic systems and how they can be successfully used for the growth of almost any hydroponic crop you can imagine. Following on this post's idea today I want to share with you some tips to use this type of system with larger plants so that you can effectively setup your own hydroponic passive farm with the least amount of effort and chance of failure. On today's post I will talk about the media and system characteristics for the raising of large plants, particularly plants like tomatoes, cucumbers and bell peppers which require large amounts of oxygen, nutrients and solid media support.

If you read the previous post you might remember that when using large plants -like the ones mentioned above - the best thing is to use a media filled container in which the nutrient solution is first close to the surface and then slowly gets used and evaporates from the nutrient solution. However it is also important here to say that there are some specific requirements for the media and some important changes that can be made to guarantee that success will be much more likely to happen.

The solid media used is better divided in two, the first media is a highly absorbent, capillary efficient media (like rice husk combined with sand 1:1) which is put in a small cup or container while the second media is a non-absorbent very capillary deficient media like gravel which is used to occupy the rest of the available space. Other coarse media can also be used to fill the rest of the container like vermiculite or other types of rocks. The important thing here is that the whole media must NOT be efficient at capillary absorption because this will make the whole media wet all the time and it will drown the roots since the "air space" will be non-existent.
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You can follow the diagram above to build a system for a large plant. Note that the container for a large cucumber or tomato plant must be at least 5 gallons and solution needs to be added at a rate of about 1 gallon a month through the crops full life. Note that inserting a small PVC pipe to control volume within the container is always a good idea since you don't want to put so much solution to drown the roots and make the plant die. Mature tomato plants require a space of at least 50cm of air roots when they are older for their proper development so make sure the container you use is about 70-100 cm tall when you build your system.

Hopefully with this advice you will be able to start your first passive large-plant hydroponic garden without using any electricity. Also remember that this setup requires absolutely no EC or pH adjustments since once added the solution won't be able to be modified. This however does not cause any problems since the plants adapt to the solution and pH levels acquired. You can also increase the EC or change the nutrient ratios depending on the plant's stage when you perform the monthly nutrient solution additions to your plant's personal reservoir. Please feel free to leave any comments with your experiences with this technique !

Completely Passive, Non-Recirculating Hydroponic Systems : Yes, Its Possible

2010-08-24T07:53:00.001-07:00

Generally when we think about growing plants hydroponically we think about complex setups with water pumps, air pumps, artificial lights, environmental control and greenhouses. However, it has been shown through many controlled experiments and experiences that hydroponics can be made in a much less fancy way, so simple in fact that pumps and other such appliances that consume electricity can be effectively and totally eliminated from the growing system without the need to lose a significant amount of crop quality or yield. On today's article I want to discuss some of these extremely simple setups and how you too can effectively and efficiently grow a hydroponic crop with low cost and absolutely no usage of electrical power.

Traditionally hydroponic systems - especially in developed countries - have been extremely dependent on electricity to make them work properly. Water pumps are used to carry fresh nutrient solution towards the plants and air pumps are used to keep the nutrient solution saturated with oxygen. However the truth is that such complicated setups are actually NOT necessary for successful hydroponic growth if adequate system design is actually made. People in less developed areas of the world such as South America, China and India have been experimenting with completely passive hydroponic setups to replace the more traditional energy intensive hydroponic growth and they have done tremendous progress to achieve this goal.

Many of you are probably already thinking about all the possible problems this might have. You might be thinking that this might work for small plants - like lettuce and some herbs - but never for nutrient hungry plants such as tomatoes, pumpkins, watermelons, etc. The fact is that these entirely passive non-recirculating systems work for ALL of these plants, providing adequate growing conditions and high yields typical of hydroponic systems. Right now it is not a matter of opinion or discussion if it can be done as MANY studies and controlled experiments already show this is a reality. You can see some clear examples here, here and here.

The questions now becomes, how is this possible and how can you do it ? The answers are pretty simple. Passive hydroponics without any electricity can be done for large or small plants given that the following conditions are met :

Enough space for roots is available
Enough nutrient solution is available for all the crop's life (or it is replenished)
Enough oxygen is available for the plant's roots

If this three conditions are met you will be able to build a passive hydroponic growing system that needs NO air or water pumps to give a good yield. How can you make such a system ? The systems that have given the best results up until now are those that follow a very simple design scheme. The plant is put in an absorbent nutrient media and placed to float or stand just above the initial nutrient solution level. The level of nutrient solution slowly falls down in the beginning (due to evaporation) and then quickly as the plants start to absorb water and nutrients. As the level of nutrient solution lowers the plant roots become exposed to layers of air from which they can absorb oxygen, allowing them to effectively absorb nutrients from the below stagnant solution without those roots dying.

Most people believe that if roots are submerged in an unaearated solution they will die but this is only true if the whole root system is submerged. If a good part of the system is given an "air buffer" from which to absorb oxygen and this space remains humid, the result is a system that can absorb nutrients from the unaerated solution and oxygen from the air buffer zone. This has in fact been shown to work in many cases (you can follow the links mentioned before for some examples).
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For big plants such as cucumbers and tomatoes you would want to use a container filled with solid media to support the whole plant with the initial nutrient level being just a few inches below the surface while for smaller crops a "fixed top" idea might work much better. In the above image you can see both systems and how they evolve as the crops grow. For larger crops you might also want to replenish some solution every month so that the crops can get all the water and minerals they need if the actual container is not large enough to hold all the water the plant would use through its whole life cycle.

Without a doubt passive hydroponic systems like these ones will become extremely important in future world agriculture (especially in developing countries) since they are able to give us many of the wonderful advantages of hydroponics without the problem of complex electronic equipment, water, air pumps or an inherent dependency in the electric grid (which is not available everywhere in rural third world countries). Hopefully this information will also be useful for those looking to establish some passive and effortless hydroponic gardens to have fresh crops year round :o).

Improving Seed Germination : The Science of Seed Priming

2010-08-23T16:42:00.000-07:00

When we want to produce large amounts of plants or simply when we want to start our gardens fast and get the most out of our purchases improving seed germination becomes a large priority. One of the largest concerns of world agriculture as well as the home grower is the decrease in germination time and increase in germination percentage since both of these factors can bring great benefits. Some seeds - especially some flowers and herbs - are often quite difficult to germinate and using certain techniques to increase the rate and speed in which they sprout has been the focus of a large amount of scientific research. On today's article I will be discussing the use of priming to decrease germination time, especially what priming is, what types are available and which ones you can use to decrease the germination time of those very difficult seeds.

To understand the concept of priming we first need a good grasp at the general concept of seed germination. A seed is a dormant embryo which carries within it the potential for a new plant's life. The seed is alive, yet has a very slow metabolic rate due to the low mobility of substances within the embryo's cells. This low metabolic rate allows the seed to remain alive, yet survive extremely long periods of time (some seeds can survive even hundreds of years) before actually sprouting into new plants.

Germination - which is the process in which we awaken the embryo - increases seed metabolism and toggles the massive reproduction that causes a new plant to grow. The main mechanism that triggers this process is simply liquid water. When water gets into the embryo and hydrates its cells, it speeds up metabolism and allows the process of cell division and growth to rapidly increase. However it is not always this simple to start this process since several impairments - both chemical and physical - can exist for successful germination.

Priming is simply a process done prior to conventional seed germination which allows the inhibiting mechanism to be broken and the metabolic speed increase to begin. There are several types of priming that can be done. A seed can be submerged in simple water (hydropriming), it can be soaked in a solution of a simple salt (halopriming) or it can be set in a non-ionic solution with high osmotic pressure (osmopriming). It is not entirely well established why one technique might work better than another but certainly some species tend to respond much more efficiently to one or another.
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In general, priming offers the opportunity to almost always germinate seeds at much higher speeds without detrimental effects in germination percentages. For example, a two day treatment of parsley seeds with a PEG 6000 (PolyEthyleneGlycol) solution can reduce germination times substantially, from a few weeks to just a few days. Other seeds such as coriander might also benefit from similar treatments with PEG or with treatments with NaCl solutions. In general if you are looking to test priming on some difficult seeds you own you can try three small experiments to know which one works best for your particular seed variety and germination conditions. Do one experiment in which the seeds are simply soaked in water for 24 hours, another in which seeds are placed in a 200mg/L NaCl solution and another one in which the plants are submerged in a PEG 6000 20% solution, then let the seeds air-dry after the treatments. After comparing the results of these experiments with a control with no priming you will be able to see which priming technique is better for you and most effectively increases your seed germination rates.

To sum it up priming your seeds is a very efficient technique to increase the speed of germination without sacrificing germination rates. This methods are not very useful for seeds such as lettuce or tomato - which germinate easily - but they are invaluable for plants such as parsley, coriander or carrots which are generally much harder to germinate. If you have some seeds that have been giving you a hard time or seem to take ages to germinate then setting up some priming experiments might be the best thing to do.

My Hydroponics Calculator : Features and Objectives

2010-08-20T01:00:00.000-07:00

For those of you interested in the preparation of your own hydroponic nutrient solutions, my hydroponic nutrient calculator should prove to be a very useful (hopefully invaluable !) tool to complete this endeavor. Within the following paragraphs I want to talk to you about the main objectives and uses of my calculator as well as some of the confusions that arises when people new to hydroponics and the chemistry of nutrient solutions starts to use it. After reading this you will be able to know precisely what my calculator does, how it can be useful to you and what the calculator simply doesn't do.

My hydroponics nutrient calculator (hydrobuddy, which you can get here) is a tool designed to aid people to prepare their own hydroponic nutrient solutions in a straightforward and easy manner. The idea of the calculator is to make all the mathematical calculations needed to go from a desired formulation composition to a given weigh of a fertilizer salt much easier than how it usually is with excel spreadsheets or manual calculations. Hydrobuddy therefore allows a person to know exactly how the addition of a given salt affects the concentration of a certain number of elements within a hydroponics solution, allowing the user to select and use the salts that precisely fit his/her desired formulation.

The main function of hydrobuddy is to take a given formulation specifying the concentration of all the giving nutrients as ppm and translate it into the necessary weights of salts or fertilizers needed to achieve these concentrations. It is however important here to note that these ppm values have NOTHING to do with the ppm values read by your EC meter. The values an EC meter reads as ppm are TDS or salinity measurements that correspond to the concentration of a sodium chloride solution of equivalent conductivity. This measurement has nothing to do with the ppm values used to specify the concentrations of the different nutrients within a solution.

Hydrobuddy also allows you to do some other very interesting things such as the calculation of salt weights for concentrated (1:100) stock solutions and the use of the "straight addition" method that allows you to calculate the weights of salts you need to add directly to a reservoir to arrive at certain concentration levels. Hydrobuddy also contains a "salt to formulation" feature which allows you to input a given weight of a salt or fertilizer and obtain the ppm values you would arrive to within your solution. This should be especially helpful for those of you looking to use hydrobuddy as a way to calculate the concentrations you get when you using specific weights of commercial fertilzers; it is also great if you want to manually tweak your calculation results if the calculator doesn't give you the salt proportions you desire.
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The calculator also has a "nutrient log" feature that allows you to keep a record of how your hydroponic solution evolves, warning you when it is time to change solutions in recirculating systems or when pH swings are too wild. Hydrobuddy also allows you to use the "run to waste" option to login the pH and EC in-out measurements of your system to keep a record of how it evolves as a function of time. The nutrient log allows you to plot the evolution of your hydroponics system and quickly realize and correct any problems that might be happening.

If your water is very hard or if you have other problems such as high nitrate concentrations, hydrobuddy allows you to input your water quality parameters by pressing the "water quality" button, letting you take into account the hardness and quality of your water when preparing hydroponic solutions.

As you see my hydroponic calculator allows you to do many things easily which would definitely take a long time to do if done manually or with excel spreadsheets. The calculator allows you to quickly change formulations, used salts, custom fertilizers, etc without having to do a lot of effort. The checklist interface and the ability to save and load formulations makes the program ideal for those of you who do a lot of hydroponic growing with custom solutions but don't want to go through all the math or spreadsheet changes every time the formulation needs or when some nutrient sources need to be changes.

My Hydroponic Calculator Tutorial : Saving and Loading Formulations and Recipes

2010-08-19T01:00:00.000-07:00

One of the greatest features of my hydroponic nutrient calculator (which you can get here) is the ability to save and load recipes and formulations into the software. These options open up a lot of possibilities and allow you to quickly and effectively modify your previous work or get the information you need for the preparation of new reservoirs or stock solutions pretty quickly. However for many people the use of these features is not that straightforward, reason why this tutorial focuses on showing you how you can exactly use the different buttons to save and load different formulations and recipes.

First of all we need to make a clear distinction between what I call a "formulation" and what I call a "recipe". A formulation is simply the group of desired values of concentrations you want to achieve for the different nutrients within your final nutrient solution. A formulation does not deal with weights or specific salts but it mainly specifies the concentrations of the different nutrients expressed as elemental ppm values within the solution. A recipe - on the other hand - includes the results of a calculation for a specific formulation, reservoir volume and a specific set of salts, the recipe tells you exactly how much of each salt you need to add in a given volume of water to prepare a given final or stock solution. So the formulation contains merely the concentrations you want to achieve while the recipe contains the amounts of salts needed to weight to achieve a given concentration on a given reservoir or stock solution setup.
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The image above shows you the areas within the calculator that deal with the inputting of the formulation, the saving/loading of formulations and the saving of recipes. After you specify a given formulation within the formulation area, you'll be able to save it using the "Add Current" button, which simply adds your formulation to the "quick load list" drop down menu right below it. Additionally you can add an external formulation by inputting the exact filename next to the "Add External" button and clicking this button. Remember that any external formulation files you want to add must be placed in the exact same folder as the hydroponic calculator's executable. Once you restart the program, the quick load list will be lost but you will be easily able to repopulate it using the "Load formulations" button which adds all the previously saved formulations to the quick load list.

One of the most useful features of this implementation is that you can easily share formulations with other people simply by sharing with them the files created by the calculator. When you use the "Add current" button, a file is created within the calculator's folder containing all the necessary information for the calculator to interpret the formulation. If you want to share your formulation just send this file to the person you want to share it with and tell him or her to load it using the "add external" button and field after adding the file to the calculator's folder.
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Another very interesting feature is the ability to save recipes. Once you select the salts and do the calculations for a given nutrient solution formulation you will be able to save all the results using the "Save Results" button. This creates a file within the calculator's folder with all the necessary salt weights and instructions necessary to carry out the preparation. You can now print this file and use it when you are preparing the formulation or you can share it with others so that they will be able to reproduce your recipe with the exact same salt additions, volumes, etc.

As you see, the calculator provides you with a great set of features that allow you to easily save/load formulations and save and share recipes for hydroponic culture. Using the above mentioned features you should be able to save your formulations, save modifications of your formulations, quickly load formulations using the quick load menu, load external formulations onto the quick load list, save recipes and share your recipes and formulations with others around you who might also be interested in them. This is a great tool if you are sharing knowledge and the preparation of nutrients within a forum since others will be able to easily load and checkout your formulations and modifications without a lot of effort.

Cobalt in Hydroponics : Better or Worse ?

2010-08-18T01:00:00.000-07:00

On yesterday's article we talked about silicon, one of the most beneficial non-essential nutrients you can use in your hydroponic crops. Although Silicon has proved to give marked benefits in peer-reviewed scientific studies, other elements are usually commented on being beneficial without a thorough investigation around current scientific literature. One of this particular cases is Co, with this element being often portrayed as a way to "increase flowering" or "increase fruiting", something which studies have shown to be false for several different plant species. On today's article we will talk about cobalt, its potential use in hydroponics, the conclusions of the studies that have been done and the potential danger involved with the use of cobalt in hydroponic solutions.

Cobalt is a transition metal from the same group as Rhodium and Iridium with chemical properties similar -yet quite different- to these other elements. As a chemist specialized in the area of organometallic chemistry - and especially through my work with this group - I have always enjoyed the chemistry of this element. Cobalt has many uses in pigments, radiotherapy, batteries, etc. Biologically its most important role comes as the metal center of the vitamin B12, cobalamine, which is essential to human life. Vitamin B12 is a large coordination complex in which Cobalt is tightly bound by an organic macrocyle, interestingly enough, this is one of the very few examples of a carbon-metal bond in nature with one of the axial ligands of cobalamin being a methyl organic group (in methylcobalamin at least).
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So now that we know that cobalt is an essential part of a vitamin, it may seem obvious to use it as a minor constituent of our hydroponic formulations. However careful studies have shown that - if cobalt is needed by plants - it is only needed in the most minute quantities with concentrations of only 5 ppm already being markedly detrimental to plant growth (L.Gómez shows this effect in two studies in both lettuce and tomato). Other studies in the lower concentration range (>5 ppm) are contradictory and none show conclusive evidence that the additions of cobalt may be a good idea to increase plant yields in general.

Some people argue that cobalt is essential for some nitrogen fixing bacteria and that plants that rely heavily on these organisms might see improvements with cobalt additions not because of their "personal use" but because of the added benefit of having a healthy microbial population. Although these claims seem to "make sense" to a certain extent there haven't been any studies that confirm that this is true and that a strong and obvious effect exists due to the addition of cobalt to a nutrient solution. If anything current studies point to the fact that cobalt additions can be detrimental and that -if beneficial- it would only be in the smallest quantities which might already be present in your formulation through mineral impurities.

You have to take into account that most people and companies use fertilizer grade chemicals for the preparation of their hydroponic formulations (otherwise it is not cost effective). These chemicals are most of the time around a purity of 80-98% with most of them being in the 95-98% zone. Since some of these minerals hold cobalt as some of their natural impurities (copper and manganese salts for example) it is not surprising if adequate cobalt levels are already present in your solution through the mere impurities you introduce with your own formulations.

In the end it seems that cobalt additions are unnecessary and the person doing them runs the risk of decreasing their yields and possibly causing a toxic accumulation of this nutrient within the plant's system that may later be detrimental to the consumer's health. In this case the no-harm principle should apply, if a given additive is suspected of having detrimental effects then avoiding it is the best possible course of action while conclusive evidence of any positive effect (and the dose in which they are achieved) is revealed. Right now we know plants grow very well without additions of Co and we also know that even low concentrations of Co are not beneficial.

Silicon in Hydroponics : What Silicon is Good For and How it Should be Used

2010-08-17T01:00:00.000-07:00

Certainly if you have been involved with hydroponics for a while or even if you have just started to research this awesome field you might already know that science has only discovered a handful of elements to be necessary for plant growth. From the first 92 elements of the periodic table, plants have only been proved to require C, H, O, N, K, P, S, Mg, Ca, Fe, B, Cu, Mo, Zn and Mn for their adequate growth. However it is certainly true that some other elements have proved to be beneficial - in certain quantities - for the development of several different crops. Such elements include Co, Si and Na. On today's article I am going to introduce you to Si, the way in which plants absorb it, how it should be administrated and the positive effects it is bound to have on your hydroponics plants.

Silicon is definitely one of the most abundant elements on the Earth's crust, forming - with aluminium - a very large portion of the earth's heavier elements. Silicon is mainly present in nature as the silicate ion (SiO3(2-)) forming solids with different degrees of polymerization known in the geological world as silicates. From these silicates we have a very large variety of minerals, from the aluminosilicates formed with aluminium to the very fine quartz particles (white sand) making up some of the most beautiful beaches throughout the world.

However when thinking about silicon and our plants we need to think about the way in which plants would be able to absorb this element. The minerals in which silicon is found are quite insoluble at room temperature and for this reason they cannot be absorbed efficiently by plants. If we want our plants to get some silicon we need to provide it in a form which is soluble and readily available for absorption. Such a form is sodium silicate (Na2SiO3) usually available as a pure solid or a solution in water called "liquid glass".
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Studies in the field of hydroponics have shown that different types of cultivars such as wheat, tomatoes and cucumbers react positively to a moderate addition of silicate ions. When water glass is applied at a concentration of around 100pm (measured as SiO2), positive effects are found including increased weights of fruits, increased nutritional composition and - most importantly - a very important increase in the resistance to bacterial and fungal diseases. It seems to be that plants use the silicate ions to "line-up" their cell-walls offering a strong additional mineral resistance to any incoming pathogens that would want to get into their cells. Since plants lack and active immunological system, passive measurements like this which increase cell-wall strength are likely to be key to increase disease resistance for many crops.

However most people are quite careless about the way in which they apply this "liquid glass" since they are mostly unaware of the very sensitive equilibrium that takes place to maintain silicate ions in solution. Silicates are by definition very insoluble and the acidic pH in hydroponics is bound to cause some precipitation of different reaction products of this ion with other ionic species present within the hydroponics solution. The silicate ions can also form silicic acid and start to polymerize into complex macromolecular constructs. As a matter of fact, several studies do include information about the problems with drip systems, sprinklers, nozzles, etc, when using silicate ions since they tend to precipitate easily outside the hydroponic solution.

I would suggest - and so I have done with my own systems - that it is better to apply small quantities of silicate ions every 2-3 days, instead of applying a large amount during the beginning process. Applying a large amount of "liquid glass" (the 100ppm for example) would most likely end in most silicate falling out of solution and only a small part becoming available for plant absorption. I believe that the best thing to do is apply about 5ppm (measured as SiO2) every 2-3 days until the solution needs to be changed. This provides both higher stability and a better control over the solubility of this tricky ion within the hydroponic solution. Of course this is purely anecdotal evidence and no controlled study has yet shown this to be better. If you want to obtain results as those of the scientific literature available then applying the 100ppm on every reservoir change might be the wisest thing to do.

The NPK Mistery - What Do These Numbers Mean and How are they Calculated ?

2010-08-15T04:24:00.000-07:00

When you go into a forum about hobby hydroponic or soil growing one of the first things you will notice is that there is a big confusion regarding the meaning of the traditional NPK notation and the way these values are actually calculated. Some people believe this is supposed to be merely an N to P to K ratio measurement while others erroneously use ppm information directly to get their NPK fertilizer information. On today's post I want to talk about the real meaning and nature of the NPK measurement as it is used in traditional agriculture, how it is calculated and what it tells us about a fertilizer. (below a fertilizer made with pelletized nutrients in clay, traditionally described using the NPK ratio, this ratio is important because it is necessary to know how much is clay and how much is fertilizer)

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The NPK measurement was invented as a way to gauge the quality and concentration of the 3 most important nutrients relevant in agriculture within a particular solid or liquid fertilizer. These three numbers represent the percentage composition by weight of any given fertilizer, telling us its percentage composition of N as nitrogen, K as K2O and P as P2O5. The reasons why K2O and P2O5 were used to represent potassium and phosphorous instead of referring to the simple quantities of these elements are that, first of all, the traditional analysis methods used to determine K and P give the values of the oxides in a more straightforward manner and second, the actual percentages of K and P when expressed as the oxides give "good ratios for the plants in soil" when the values are close to the value of N (making comparisons easier).

It is now important to note that the NPK reading must be calculated taking into account the weight of the given nutrient within the solution and the WHOLE weight of the fertilizer used. For example if you have a liquid concentrated fertilizer that has a composition of N = 12000 ppm, K = 20000 ppm and P = 4000 ppm which was prepared with 200g of added salts. The NPK ratio of this solution would be :

Total Solution Weight = 1000g (1L of water) + 200g (added salts)

N = 12000 ppm = 12000 mg/L = 12 g/L
K = 20000 ppm = 20000 mg/L = 20 g/L
P = 4000 ppm = 4000 mg/L = 4 g/L

Percentage of Nitrogen = (12g/1200g)*100 = 1%
Percentage of K as K2O5 = (20g/1200g)*1.2046 (K to K2O conversion factor)*100 = 2%
Percentage of P as P2O5 = (4g/1200g)*2.2914 (P to P2O5 conversion factor)*100 = 0.76%

The final NPK ratio is therefore 1-0.76-2. As you see you need to know the total weight of the solution and the elemental composition in order to be able to obtain this number. It should also be clear that the traditional NPK ratio is a PERCENTAGE COMPOSITION measurement and NOT a mere comparison of the ppm concentration ratios of N, P and K. Knowing a fertilizer's NPK not only allows you to know the ratio between these three elements but it also allows you to know how much of each one is contained within the solution so that the relative strength of different fertilizers can be calculated.

The traditional NPK ratio however has very limited use in hydroponic cultivation since it was invented to gauge the quality of soil intended fertilizers. Nonetheless it can be used to compare the relative strengths of different fertilizers and the ratio of the three main nutrients within them. However it should be clear that if you want to communicate a measurement that compares ppm concentration ratios you should not refer to this as an NPK measurement since this will cause confusion against the "traditional NPK" which was explained above. In hydroponics it would be easier to talk about ratios of ppm which should be expressed as N/K-P/K-1 for example which would give us the ratio of N to K and P to K without giving information about the percentage composition of the solution.

Truly Cleaning Your Hydroponic System : The Fenton Process and Chemistry

2010-08-13T02:00:00.000-07:00

When most people clean their hydroponic systems they use a hypochloride or hydrogen peroxide wash that they think kills all the bacteria and potentially hazardous substances within their setup. However few people realize that - although the system is indeed sterilized - the bast amount of harmful substances and chemicals (even those coming from the plastics themselves) remain intact after the attack of either hypochloride or peroxide. For example, many of the harmful plasticizers and complexes used for the making of PVC and other polymers remain intact after a rigorous wash with these two cleaning agents. So what can we do to truly clean our hydroponic systems and get rid of all the bad things that may be quietly waiting their turn to get into our plants ? The answer comes in the form of a very well known process used world-wide to clean water supplies from toxic chemicals : the Fenton process.

In the late 19th century, Henry John Horstman Fenton discovered a chemical process which was able to oxidize the most resilient organic molecules and turn them into harmless chemicals. As a matter of fact, Fenton's process was so revolutionary that it sprouted a whole new area of research called Fenton chemistry in honor of its discoverer. What was this wonderful discovery ? Within the next few paragraphs you will learn what the Fenton reagent and process are all about and - most importantly - how this process can help you clean, I mean REALLY clean, your hydroponic system between growth cycles.
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If you have been preparing your own hydroponic solutions and you have been using hydrogen peroxide then you already have most of the things you need to do some Fenton chemistry. The process basically works by adding a source of iron ions (they must NOT be chelated, like iron (II) sulfate) and hydrogen peroxide to a water solution. The iron ions then catalyze a series of reactions that generate powerful oxidizing radicals that destroy almost all harmful organic substances within your system. The iron ions are KEY to the Fenton process since they allow peroxide to generate this extremely reactive substances that are never present when peroxide exists on its own (reactions shown above). Research has found - for example - that phenol (a common chemical used as a model contaminant) remains unchanged in the presence of large concentrations of hydrogen peroxide while it is quickly destroyed in the presence of the Fenton reagent (Iron ions plus hydrogen peroxide). So what do you need to do ?

First of all you should add about 0.2g of Iron (II) sulfate per liter of solution you will be using to clean your system.
Then you should set your pH to a level between 3 and 3.5 using a STRONG non-organic acid such as nitric or sulfuric acid. You should NOT use citric, acetic or phosphoric acids since they lower the effectiveness of the Fenton reaction.
Add as much peroxide as you would add to regularly clean your system. About 70mL of 50% hydrogen peroxide for each liter of solution works very well.
Circulate the Fenton cleaning solution for at least 6 hours.
Wash your system with water until no Fenton solution remains.

It is key for you to use a non-chelated iron source since chelated iron sources such as FeEDTA or FeEDDHA do NOT work well since the chelate does not allow the iron ions to properly react and participate in the Fenton chemistry that should be going on. The pH adjustment step is also vital since a pH above 5 would cause the formation of FeOH3 instantly upon the addition of H2O2 with the subsequent catalytic decomposition of all the H2O2 by the iron hydroxide (this is NOT something we want !). After you use the Fenton reagent to clean your system you will be certain that a lot of the harmful organic molecules that were present have been destroyed and your system will now be able to play as a sterile and harmless host to your new set of beautiful plants.

Iron Sources in Hydroponics : Which One is the Best ?

2010-08-12T02:00:00.000-07:00

Definitely one of the most important problems dealing with the stability of hydroponic solutions is the availability of the iron (Fe+2 or Fe+3) ions. Since iron easily forms hydroxides and insoluble salts with other ions present in hydroponic media it becomes essential for us to provide iron in a way which is accessible to the plant and does not "come out" of the hydroponic solution through precipitation. Within the next few paragraphs I will talk to you about different iron sources available to hydroponic growers and which source is actually the best one we can use in hydroponic nutrient solutions. We will go through the different factors that make an iron source better or worse and finally we will be able to choose one as the ideal source for our nutrient needs.

What is the problem with iron ? The main problem we have with iron is that - unlike most other transition metal ions in hydroponic solutions - it is a very strong hard lewis acid which easily forms insoluble salts with many of the hard lewis bases within our hydroponic solutions. When iron is added to a nutrient solution in its "naked" form (for example when adding iron (II) sulfate) the ion easily reacts with carbonate, phosphate, citrate, oxalate, acetate or hydroxide ions to form insoluble compounds that make the iron effectively unavailable to our plants. To put it in simpler terms, iron ions have a chemical nature which is similar but opposite to that of many other constituents of our hydroponics solution meaning that when they meet together they form a "perfect match" that does not easily separate.

There is not only a problem with the higher inherent chemical match-making of iron with the anions present within the solution but we also have the problem that iron is always present at a much higher concentration than the other micronutrients. So even though some transition metals like copper would suffer from similar problems the fact is that they do not simply because of their much lower concentration (Fe is usually around 3-5 ppm while Cu is usually around 0.05-0.01 ppm).
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The solution to this problem is actually easy and comes in the form of chelating agents that "wrap" around the iron ions and make them disappear to anions that may want to form stable salts with them. There are many of these chelating agents with the most commonly used being EDDHA, EDTA and DTPA. They are different due to the fact that their stability is different and their abilities to dissolve iron are also different. While all of them make sure iron stays within solution EDTA only allows this to happen until pH 5-6 while, DTPA takes it until about 8 and EDDHA to more than 9. The most stable iron complex is definitely FeEDDHA but this does not make it necessarily the best candidate for hydroponic growing.

The fact is that although EDDHA binds iron much more strongly it decomposes easier within the hydroponic solution than EDTA or DTPA (this is due to the fact that EDDHA is composed of several different isomers, some of which are not very stable), reason why this complex appears to be but is not the best solution for hydroponic nutrient solutions. The best compromise between stability and durability is earned by DTPA which gives us a very stable complex and a strong resistance to decomposition. So next time you are looking into getting a new complex for your Fe needs, try FeDTPA (this salt can also be used with my hydroponic calculator).

Chemical Buffers in Hydroponics : What is the Best, Cheapest Buffer

2010-08-11T06:40:00.000-07:00

One of the biggest questions people ask when starting to grow hydroponic crops deals with the stabilization of pH and the use of chemical buffers to keep pH levels at acceptable ranges during long periods of time. The question is very relevant since changes in the pH of a nutrient solution can cause a lot of problems related to nutrient availability and having to add large quantities of acids or bases to correct the deviations is also not something plants will enjoy very much. What we need to do then is to keep pH levels within an acceptable range, for a period at least long enough to last a few weeks.

On previous posts I have talked about the way in which I do this using ion exchange resins but these can be too expensive or hard to find for most hydroponic growers out there. More over, chemical buffers are often much easier to use, get and apply although their actual mechanism of action is much less effective and much more aggressive than that of the ion exchange resins. A chemical buffer is mainly a substance which is added into your solution that distributes itself as different ionic species that can react either with acids or with bases at certain pH levels. The buffer however is also available for your plants to absorb and therefore we are limited to chemical buffers which are not phytotoxic (toxic to plants) and which allow us to control pH within the range we want.

From the very large library of chemical buffers available to the modern chemist, only a handful are suitable for their use in hydroponics and - even then - most of these are actually not practical in the sense that they are extremely expensive for the home grower. Certain organic buffers like MES offer extremely good results although they are hard to buy and very expensive, a reason why they are not used widely in hydroponic culture (this buffer is used mainly on hydroponic research where precision - and not cost - is the main determinant factor).

The buffers we are left with are then very simple organic and inorganic substances that have low phytotoxicity and some compatibility with the other ions present in our hydroponic setup. From these ions phosphate species, citrate species and carbonates are the most important ones we can use within our hydroponics setup. However we are limited by the actual concentration values of each we can use and for this reason we cannot have unlimited buffering capacity from these sources.

Which one is best ? We can actually carry out simulations to show us the pH vs acid-base addition for different hydroponic solution constitutions using mathematical equations. Running these simulations requires the solution of highly complex systems of equations which contain all the information relative to the chemical equilibrium of all the different existing ionic species. The below shown simulations were carried out using the Mathematica computer program (all solutions are assumed to be adjusted to an initial pH of 5.8 with a strong acid or base).
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The blue curve represents the behavior of a poorly buffered hydroponic solution with only about 0.002M phosphate concentration (about 50 ppm of P). The red and yellow curves represent two solutions with increasing levels of carbonate showing us that if you are battling pH increases, having more carbonate will definitely help you deal with this. However it is also clear that carbonate concentrations at pH 5.8 are restricted to around 100 ppm since values above this are bound to cause toxicity due to the very large presence of the hydrogen carbonate ion. The green curve represents an increase in the amount of phosphate from 0.002 to 0.004M (about 100 ppm) with carbonate, showing us that phosphates are not good at buffering increases towards the upper side but they do increase buffering towards acid territory. Overall I also noticed that citrate concentration increases to the maximum threshold allowed by calcium citrate solubility did not afford a very good buffering effect with only a mild effect that prevented shifts towards the downside.

In the end, the conclusion seems to be that in a regular hydroponics system where pH increases generally happen towards the upside it is better to use carbonate as a buffering agent than to use citrate or phosphate although phosphate at its regular concentration in hydroponic does provide some buffering against pH moves (without phosphate increases are much more dramatic). For this reason I believe that a phosphate/carbonate buffer seems to be the best choice for most hydroponic growers, taking care to keep the concentrations at levels that do not cause precipitation or phytotoxicity problems.

Preparing Your Own Hydroponic Nutrients : A Complete Guide for Beginners

2010-07-06T14:37:00.000-07:00

Chances are that if you are into hydroponic gardening and you live in Europe or in the US you have been buying your nutrient solutions from one of the many hydroponic nutrient sellers available locally. Generally people do not prepare their own nutrients because they consider this task "terribly difficult" and they prefer to keep buying previously made formulations so that they don't have to deal with the technical problem of making their own fertilizers. What most people don't realize is that the profit margin of hydroponic nutrient producing companies is HUGE. You would be surprised to know that each one of those concentrated nutrient gallons you buy costs only a few dollars to make (sometimes even only pennies) and you are probably paying a few times what the whole fertilizer is worth.

Obviously if you are going to be growing plants for a long time or if you simply want to grow a large garden the buying of this commercial nutrient solutions is not an option and starting to make your own formulations - adjusted to your own needs - becomes the main priority. On today's article I will be speaking to you about how to prepare your OWN solutions using my nutrient solution calculator, carefully explaining to you what you need, where to buy it and what you should expect. I will guide you through making your own first A+B solution by YOURSELF getting all the chemicals and utensils you need easily and economically.

So what do you need to make your own nutrients ? The list below shows you the things you will need to start making your own A+B solutions. You will notice that you will need two scales since we are going to have to weight two "nutrient sets" with different precision, micro nutrients (which are used only in small amounts, need to be weight more precisely) and macro nutrients (which are used in larger amounts and therefore need scales with larger capacity).

Scale that can weight down to 0.01 g at a +/- 0.01g precision (something like this is perfect, just search 0.01 g scale on ebay to view similar products)
Scale that can weight up to 1kg at a +/- 0.1g precision (something like this)
Two Empty one gallon containers with caps
Plastic Spoon
Plastic small container (to weight salts)
A source of RO or distilled water (your tap water will NOT work)
Download my hydroponic nutrient calculator here.
Download the formulation you will be using here.

Now these are the chemicals you will need (an online purchase link is included for each one) :

Yara Brand Calcium Nitrate (here)
Magnesium Sulphate Heptahydrate (here)
Potassium Nitrate (here)
Copper Sulfate Pentahydrate (here)
Potassium Monobasic Phosphate (also known as mono potassium phosphate) (here)
Manganese Sulfate Monohydrate (here)
Zinc Sulfate Dihydrate (here)
Sodium Molybdate (dihydrate) (here)
Boric Acid (here)
Iron EDTA (NaFeEDTA) (here)

These chemicals can be bought in a variety of places but there is a link next to each one showing you a link where you can actually make the purchase. Often it is also possible to get these chemicals on ebay. The purity may not be as guaranteed as when purchased from a regular supplier but it is good enough for practical purposes in hydroponics. This is an example of Sodium Molybdate of a decent quality being sold there.

Of course you may see right now that the initial investment might be significant (from 100 to even more than 500 USD depending on whether you buy 50lb or 1lb quantities of macro nutrients) however after this purchase you will be able to produce more than one hundred gallons of concentrated A+B solutions which would cost you more than 10 times the price you will be paying if you bought them commercially. After doing the math you will see that this is a GREAT way to save money and produce your own solutions ! Hey you could even start selling to the neighbors ! :o)

After you buy the chemicals simply open my hydroponic calculator and load the general_beginner.txt nutrient formulation file you downloaded earlier on the calculator (use the "add external" button on the "Desired Formulation" tab. Then click the A+B solution button and select the "calculate weights for specific stock solution volume" option and input 1 (choose gallon) on the edit box above it. Now go to the "nutrient salts used" tab and select the salts mentioned above (make sure you select Yara Calcium nitrate instead of the regular one) .It is now time to go back to the "desired nutrient formulation" tab and press the "calculate formula !" button. Your screen should look like the picture shown below.
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Now that you have calculated the weights needed you should go to the "calculation results" tab where you will be able to find the weights of the different nutrients you need to prepare the solution. The results of the calculation are showed below. You should now follow these steps to prepare the solutions :
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If the chemical weights more than 10g weight it on the "less accurate" 0.1g scale. If it weights less on the "higher precision" 0.01g model.

Fill each one gallon container with half a gallon of RO or distilled water
Weight one salt on the container you set apart for measuring. Make sure you always DOUBLE check the weights and the appropriate A or B gallon container you need to add the salt to.
After you measure the salt transfer it to either the A or B gallon container (depending on which one it should go into). Use a little bit of water (RO or distilled) to transfer any remains that cannot be easily added and dry the container you are using to weight before measuring the next salt
Shake the container where you added the salt and make sure it is fully dissolved before measuring and adding the next one.
Do the same as above for all the salts
After you are done adding the salts add half a gallon of water (again RO or distilled) to each container
Then seal the containers and shake them vigorously
You have just prepared your first batch of self-made nutrient solution ! (Yey !!)

The above formulation is a general multi-purpose blend that should allow you to grow a large variety of plants. You simply need to add 10mL of A and 10mL of B for each final LITER of nutrient solution. You should use your pH meter and EC meter to adjust these values as you do with your regular commercial nutrients.

It is very important now to keep your chemicals stored in air-tight container in a dark and cool place. Some chemicals like calcium nitrate will absorb moisture and become useless if you leave them in contact with air for prolonged periods of time !!!

Of course, once you are more comfortable with preparing your own nutrients you can go to the A+B+C tutorial or research the available literature for some custom formulations available to grow each one of your plants under its favorite nutrient levels. I hope this tutorial has allowed you to reach a new level in your hydroponic gardening experience, hopefully accompanied by a drastic reduction in your soil-less gardening costs !

Note : Please leave a comment with your experience with the tutorial and with any links, phone numbers or addresses of your local chemical suppliers (if you have already located some you like). I will add them to a future feature of the calculator which will hold a chemical supplier global directory :o).

Preparing A, B and C (three part) Concentrated Nutrient Solutions, a Tutorial for my Hydroponic Nutrient Calculator

2010-06-24T09:23:00.001-07:00

On the last tutorial dealing with my hydroponic nutrient calculator we learned how to prepare A and B concentrated nutrient solutions for any given formulation we would like. We learned about the different incompatibilities that need to be avoided and why this leads to the creation of two separate solutions. After learning how to prepare these solutions many of you may be interested in knowing how to make the three part formulations commonly made available by most hydroponic nutrient sellers. For example, companies like Advanced Nutrients and General Hydroponics offer three part formulas which are meant to be combined to ensure adequate nutrition during a plant's whole growing cycle. Today I am going to explain to you the main objectives of a three part formula, the difference with a two part formula and how you too can prepare your OWN three part nutrients to feed your hydroponic plants through their whole vegetable, flowering and fruiting cycles. As with the past two tutorials you will need to download my hydroponic nutrient calculator available here for free.

What is the difference between a 2 and a 3 part formulation ? What we need to understand here is that plants usually have different needs through their whole life cycle and therefore they require different nutrient ratios as they grow older and face different stages of their development. With a two part concentrated nutrient based formulation we can only vary this ratios in a certain way and doing any variations outside this scope will not be possible. With the default approach in my calculator you can vary nutrient ratios by varying the "desired formulation" every time you prepare your reservoir again (since most nutrients are added directly) but with the A and B concentrated solutions you are bound to "stick" to a certain set of concentration values for each nutrient.
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The solution to this problem is quite simple and this is what most commercial fertilizer sellers have come up with. You have two solutions with the same salts but varied nutrient ratios and a third solution that remains constant. What we have then is two possibilities of final compositions A-B and C-B and a whole new possibility for nutrient ratios by combining A-B-C. What is done most of the time is that A-B becomes an ideal formulation for vegetative growth while C-B is an ideal formulation for fruiting. When you start to grow you generally do so with A-B and then you move towards C-B by increasing C and decreasing A as reservoir changes happen.

In my program this sort of solution scheme is easily achieved. What you need to do is simply to have two desired formulations, one for ideal growth and one for ideal flowering and then you just need to make two sets of A and B calculations where B is shared amongst the two. To do this we will first load the general_growth_soluble.txt and general_fruit_soluble.txt desired formulations as indicated on the tutorial for the preparation of A and B formulations (you can download them here and here). After loading the general_growth_soluble.txt composition you should have the formulation composition displayed below.
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Then follow the same procedure outlined on the "A and B solution tutorial" to arrive to the salt-weight compositions of the A and B formulations (save the results using the "save results" button) . Now load the general_fruit_soluble.txt formulation and repeat the calculation, also saving your results. A summary of the results of both calculations is shown in the image presented below. You will notice that both calculations share the same weights for the B solution (meaning they use the same B solution) while the composition of the A solution changes. What you have now is a basic three part formulation. You could now think about a regime to change from an A-B growth solution to the C-B fruiting solution in the amount it takes your plants to bear fruit.
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For example, if your plants took aproximately 5 reservoir changes you would then use different quantities of A and C to go from a 100% A feed to a 100% C feed during that time. A timeline if it takes your plants 5 reservoir changes to get to fruiting is shown below. Note how in the beginning we use 10mL of A per liter and then in the end we use 10mL of C per liter, meaning that we have done a full gradual change from a growth to a fruiting formulation.
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As you see from the above, you can easily use my hydroponic calculator to prepare your own three part concentrated nutrient blends which you can use to build your own nutrient schedule to go from vegeative growth to fruiting. However if you are currently using a fixed composition of a three part commercial nutrient blend then you can easily prepare an A and B solution to replace it, three part nutrients are ONLY needed when you want to do a varying schedule like the one introduced above, using three part nutrients without doing this is simply an overcomplication since a fixed composition can be prepared using just two custom concentrated solutions.

Preparing A and B Solutions Using My Hydroponics Nutrient Calculator

2010-06-22T08:03:00.001-07:00

The default way in which solutions are prepared using my hydroponic nutrient calculator involves the direct addition of some component in your nutrient reservoir plus the preparation of some micro nutrient and iron concentrated solutions from which 10 and 100mL are added per batch. This way of preparing solutions is especifically suitable for people with large reservoirs and commercial hydroponic growers since when reservoir levels go above 4 cubic meters all nutrients can be added directly to the reservoir, saving the time and cost of preparating any concentrated solutions. The approach is also good for people with small reservoirs since you can prepare the micro and iron concentrated solutions, dissolve other salts directly and in the end you will have a very accurate amount of micro and macro nutrients prepared with your own custom formulation. However upon the request of several people I implemented an approach that allows people to prepare traditional formulations using an A+B concentrated nutrient solution approach in which two concentrated solutions at a 1:100 ratio are prepared and then simply diluted to prepare the final hydroponic reservoir's contents. On today's post I will discuss this approach and how you can use it if you have the appropiate nutrient salts. Please download my hydroponic nutrient calculator here to follow this tutorial.

Before we go into the main aspects of the preparation of concentrated solutions we must first understand the incompatibilities that are present within concentrated solutions that restrict the salts that can be used. The program checks for these incompatibilities automatically when using any of the saved salts and for this reason custom salts cannot be used for the A and B custom preparation. The main incompatibilities are shown on the image below. Mainly what we want to ensure is that certain ion pairs that would precipitate insoluble salts are never present together. For this we should avoid putting calcium and sulfate ions together as well as calcium and phosphate species and iron and phosphate species.
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What we have left is the layout shown below that describes the general distribution of ions relevant to solubility of an A and B hydroponics formulation makeup. As you see what we achieve by dividing the concentrated solution into two is to keep away the ions that would precipiate when put together. This of course also restricts our ability to use iron sulfate and a different source of iron, either a chelate (FeEDTA, FeDPTA, etc) or iron nitrate must be used. It also restricts our sources of Calcium to calcium nitrate and therefore our sources of phosphate and sulfate are reduced to potassium salts.
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Now let us use our basil_soluble.txt example to calculate the composition of the given A and B solutions needed for this formulation. Unzip the calculator and txt files to any given directory and input basil_soluble.txt under the field next to the "add external" button in the "Desired Formulations" tab, then click the "add external" and "Load Formulations" buttons and select the basil_soluble.txt formulation from the drop down menu. The end result of this process is shown on the image below. Also make sure you check the "Concentrated A and B" option so that the program calculates the results for these solutions instead of the regular method.
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After doing this go to the "Nutrient Salts Used" tab and uncheck Calcium Monobasic Phosphate and Iron Sulfate and check Iron EDTA, Potassium Sulfate and Potassium Monobasic Phosphate. Now go back to the "Desired Formulations" tab and click the "Calculate Formula!" button. The program will now calculate the volume of A and B solutions you should prepare so that it will last for 10 reservoir changes of the volume you have input under the "Desired Formulations" tab. So for this case in which we left the input as 100L the final concentrated solution volume is 10L since it will last for 10 changes of the 100L nutrient reservoir, adding 1L per reservoir change. It should also be clear that the concentration ratio of 1:100 cannot be increased due to solubility limitations of salts. The results of the calculation are shown below.
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Hopefully with this tutorial you will be able to prepare any A and B solution for any final formulation you would like. It is also clear that this approach has less flexibility than the "default" since it restricts the character and distribution of the salts used, making the use of very cheap fertilizers like calcium monobasic phosphate effectively impossible. However it also provides an "easy way" to make reservoir changes since concentrated A and B solutions only need to be prepared once every 10 times this happens. So it is clear that both approaches have their advantages and with the help of my calculator you'll be able to choose whichever approach fits you best :o)

Using my Nutrient Calculator with Commercial Fertilizers : Part No.2

2010-06-21T05:53:00.001-07:00

On the last part of this tutorial series I talked about how you could use my hydroponic nutrient calculator to figure out the ppm values of a commercial fertilizer. Today I am going to talk about how you can achieve a given ppm formulation using a commercial preparation figuring out what additional salts you would need to arrive at an adequate composition. I am also going to show how you can figure out the final concentrations of nutrients when using combined commercial fertilizers and salts and how this approach can be used to arrive at full, accurate and complete formulations for your hydroponic reservoir. In the end you will see how my hydroponic calculator (hydroponic buddy) is a great tool for the preparation of your hydroponic nutrients even if you rely solely on commercial formulations. You will need my hydroponic nutrient calculator to follow this tutorial, you can download it here.

Today we are going to use a few commercial fertilizers from General Hydroponics and Advanced Nutrients as well as a hydroponic formula to grow tomatoes. The formula - applied for tomato growth in Florida for the first cluster growth stage - can be found here. We are going to use the FloraBloom and FloraMicro nutrients from General Hydroponics (labels here and here) . As with yesterday's tutorial the first thing we are going to do is add all the custom fertilizers within the "Nutrients Salts Used" tab by using the "Add New Salt" button by entering the composition percentages found on the label and composition pages of the above mentioned fertilizers. After doing this we input the desired tomato formulation under the "Desired Formulation" tab like it is shown below.
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Once we have the formulation we select the custom fertilizers, uncheck all other salts and input a volume of 100 liters. After doing this we press the "Calculate Formula !" button which produces hte results shown below. The software also warns us about errors so we need to go to the "Warnings and Errors" tab where we see that certain nutrients are missing from the formulation. In particular we see that we are missing Zn. B and Cu. You will notice that many combinations of hydroponic fertilizers miss one or several essential nutrients for plant growth (even micro-grow-bloom combinations often miss B, Zn and Cu).
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So right now we need to add sources of these elements to have an adequate formulation. Go to the "Nutrient Salts Used" tab and select Zinc Sulfate, Boric Acid and copper sulfate and press the "Calculate Formula !" button again. This now produces the results shown below where all elements are present and the program tells us to prepare an additional 1L concentrated solution of Zinc Sulfate, Copper Sulfate and Boric Acid.
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However we see now that the formula is not very well balanced since we have a 100% excess of N and a defect in S so to achieve the desired composition it might be necessary to tweak the results slightly in a manual fashion and use some additional salts like Calcium Nitrate. To do this tweaking you should input the weight values obtained on the "Mass" boxes next to each salt's name (the mass of Zn, Cu and B salts is the mass of the concentrated solutions divided by 100 since the 1L concentrated solutions are prepared with a 1:100 dilution factor taken into account). The input and the results of the "salts to formulation" calculation are shown below.
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Now we need to increase S and decrease N. To decrease N we need to reduce the amount of the most important Nitrogen source (FloraMicro) to about half. Since this reduces the amount of Ca significantly we can now add calcium sulfate to the formulation to make up our now acquired Ca and S deficiencies. Select calcium sulfate and give it a value of 15g. After doing this you will notice that Ca and S concentrations will be much closer to the desired end values given by the original formulations. The final result is shown below. Eventhough the amount of nutrients are not absolutely the same as the ones on the formulation we were able to achieve the same "global ratios" for all important nutrient levels and the solution will now contain ALL the necessary nutrients for adequare plant growth and - in this case - especially for the first cluster development of tomato plants.
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I hope that this tutorial allows you to understand better how my hydroponic nutrient calculator can be used for the preparation of a wide array of formulas and the correction of commercial nutrient fertilizers that lack some essential nutrients for plant growth. It also shows you how you can modify the results of the automatic calculator to further correct a formula if you believe that better results and pairings can be achieved. As you see, the calculator gives you tremendous flexibility and makes the preparation of hydroponics nutrients with precise ppm nutrient values a simple exercise.

Using my Nutrient Calculator with Commercial Fertilizers : Part No.1

2010-06-19T08:53:00.000-07:00

One of the main reasons why I wanted to develop a nutrient calculator for hydroponics was to allow people to understand the amount of nutrients they are adding to their solutions and to use the calculated amounts to either use common salts to achieve the same nutrient percentages or to understand which salts are needed to adequately compliment the nutrition achieved by their hydroponic nutrients. On these posts I intend to show you how you can use my hydroponic nutrient calculator with your commercial hydroponic nutrient composition, figure out the amount of nutrients given by a certain amount of the fertilizer, adapt your fertilizer to a given formulation you want, supplement your nutrient with other salts and get a similar composition yourself with easily available salts (which are used to make your hydroponic nutrients most of the time). For this tutorial you will need my hydroponic nutrient calculator available here.

First of all, lets learn how to add a given nutrient commercial fertilizer to your list of hydroponic salts/nutrients. After you open the program go to the "Nutrient Salts Used" tab and select the "Add New Salt" button. A screen will pop up in which you can input the percentage composition values of your fertilizer. As an example, let us use the FloraBloom fertilizer from general hydroponics and add it to our fertilizer list. The fertilizer composition given on the product's label is available here. Below you can see an image of the added percentages on my nutrient calculator, note that the K2O, P2O5 check box is used as the percentage values on the label are given as oxides for K and P. After finishing the addition the "GH - FloraBloom" item becomes available in the bottom of the page.
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We are now going to calculate the ppm values for the different nutrients we would get for the recommended addition of 1 tbsp/gallon for regular growth. Since 1 tbsp is 15 mL and we assume the fertilizer density to be 1 g/mL we get an addition of about 15g per gallon of solution. We input 15 in the field next to the fertilizer name, leave the purity at 100% and go to the "Salt to Formulation" tab where we input a volume of 1 gallon. We then get the results shown below. You can see that this preparation would give us around 87 ppm of P, around 131 ppm of K, 60 ppm of Mg and 40 ppm of S. Now that you know how to get these values it becomes easy for you to know the amount of nutrients you are getting for a given amount of any commercial fertilizer simply by using the composition values available on the label.
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Getting these values is only the first and easiest thing we can do with commercial fertilizers using my calculator but you will see within the next few tutorials that much more powerful things are possible. Right now you can also get the ppm values of different mixes of commercial fertilizers as well as current ppm values you are getting with any custom regime you are using. For example you could upload the whole General Hydroponics series to the calculator and see the different ratios you can achieve with different proportions of their products.

On the next tutorial we are going to use the above mentioned fertilizer as well as a predetermined formula to determine which salts are needed to compliment the above solution and obtain a well-balanced custom formulation. After that we are going to see how we can use the above obtained ppm values to makeup our own copy of this fertilizer as well as how we can improve it. I hope you are enjoying my free hydroponic calculator and that you leave any comments you may have :o)

Possible New Features for my Hydroponics Calculator

2010-06-13T09:52:00.000-07:00

A few days after the release of my hydroponic calculator free software implementation I can tell you that I am absolutely happy with the results. The calculator had some resolution problems at first but these problems where easily fixed. After changing to a tabbed interface and by including the ability to save and load nutrient recipes I think that the calculator is on its way to become one of the most important tools for serious hydroponic hobbyists and small business owners. Right now the calculator allows you to get precise weights of different nutrients to prepare your own hydroponics solutions something which no other free software available online does. This allows people to save great amounts of money and achieve very good results around their hydroponic crops, at least when dealing with nutrients. However I believe that there is still a lot to do and for this reason I will be writing today's post about my ideas for the calculator and it will also be great to know what you have in mind :o)

There are several things I want my calculator to be able to do in the future but first of all my focus will be on everything dealing with hydroponic nutrients. The first important additions I am working on mainly deal with the ability to add custom salts to the program and obtain results of ppm concentrations achieved by placing certain amounts of salts within the solutions. Certainly being able to go from a given weight of salt or commercial fertilizer (with known percentage element compositions) to a ppm concentration will allow people to know how adequate their recipe is and - moreover- it will allow people to play with different levels of salts if they feel that the currently "automatic" salt quantity selection is not doing the best possible job. It will also allow people to "reverse engineer" their commercial hydroponic solutions by figuring out their ppm contributions, later using those on the nutrient design tab to obtain salt weights to arrive to those concentrations. By using different sources people will also be able to pinpoint with good accuracy the nutrient sources used by their favorite commercial blend.

The next big feature I am looking forward to add is a "water quality" section which will help people adjust their nutrient solution to their water quality parameters. Things such as hardness, carbonate levels, magnesium, calcium, pH, EC, nitrogen and QOD (chemical oxygen demand) might be important parameters I will take into consideration within this section. A pH and EC prediction module - which is almost finished - will help people calculate an estimate of what their final solution properties for a given formulation might be.

Even though these features are bound to add great flexibility to my calculator, I believe that right now this is only the "tip of the Iceberg" of the potential the software has. After doing this I will attempt to put all my chemical knowledge regarding hydroponics crops into practice by inputting "optional additions" that people will be able to choose when preparing their formulations. For example, you might want to choose the "hydrogen peroxide regime" option and a summary giving you usage instructions as well as detailed explanations of how much peroxide to add and when to your reservoir will be shown. Similar options ranging from "potassium silicate treatment" to "cobalt supplementation" might become available as the calculator progresses.

As you see, there is a lot in storage for this little calculator program which I am hoping to rename to something like "hydroponic buddy" once version 1.0 comes out. Right now I am working on all the features and relearning a lot of Delphi programming which I honestly haven't done extensively for almost 10 years. Do you have any suggestions for my hydroponic nutrient calculator ? Do you have any suggestions about what you would want to do with it ? Please leave any comments, questions or suggestions below ! By the way, you can get the latest version of the calculator here.

The First Free Hydroponic Nutrient Calculator Program :o)

2010-06-08T13:49:00.000-07:00

After a lot of work and effort today I have the pleasure to share with you my latest development in the area of hydroponic nutrient design and creation, a totally new and free hydroponic nutrient calculator which I programmed using Delphi. This piece of software is absolutely unique and I can guarantee that you will not find any other similar program on the internet. The piece of code I am about to release was the natural evolution of my excel spreadsheet (which comes with my free ebook) and now has a ton more features which should make hydroponic nutrient calculation for absolutely anyone a total breeze. On today's post I want to share with you this program as well as a general description of its scope, uses and improvements over the excel spreadsheet available for nutrient calculation within my ebook.

One of my main objectives has always been to design and prepare my own hydroponic nutrient solutions and to help others do the same thing. Preparing your own solutions is not only something that gives you absolute control over the composition of the nutrients you are giving to your plants but it also allows you to make absolutely HUGE saving on commercial fertilizers. Using commercial liquid concentrated solutions the cost of a hydroponic garden is usually above 0.20 USD per gallon while if you make your own nutrients this price can drop as low as 0.01 USD per gallon. Additionally people from less developed countries where hydroponics are not very well established will be able to greatly benefit from making their own blends with this sometimes being the only way to have a hydroponic crop.
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The program I am releasing today will allow you to calculate the amount of salts you need to weight to arrive to a given hydroponic formula. The features of the program and its advantages over the spreadsheet previously available are highlighted below :

Ability to calculate weights of salts for any given hydroponic formulation
No need to have excel :o) any Windows platform will do.
Flexibility ! Choose which salts you want to use to makeup your nutrient solution
The program automatically determines which salts are better than others or pairs them up adequately if you have several sources for the same nutrient
Input the volume you want in Liters, gallons or cubic meters
The program automatically determines if you need or don't need to prepare concentrated micro-nutrient and Fe solutions depending on the size of your reservoir
You can also choose to add all salts directly if you have scales with the necessary precision
Concentrated A+B solutions can be prepared
Save your solutions ! You can easily save your recipes to a text file for later printing or reference
Save salt selection
Select water quality parameters
Automatically corrects the weights of salts against your water quality analysis
Example recipe obtained using the program and the list of salts I personally use (although you may change those salts for others depending on where you live)
Automatically check for new updates
And many, many more ! :o)

As you see, this new program is a great leap forward in custom nutrient solution design and preparation for the average hydroponic hobbyist and small business owner. Hopefully with this program you will be able to prepare your own solutions or improve your previous calculations if you had been using the spreadsheet. I hope that you enjoy the new program and leave any feedback you have here. As always I will be glad to take into account and implement your requests :o)

Please Note that the Calculator is NO LONGER hosted here. Please follow this link to see the latest changes and download the latest version of the calculator

Building Your Own High-Power LED Grow Lights for Hydroponics

2010-06-07T01:00:00.000-07:00

You will often hear in the world of hydroponic growing that Light emitting diode (LED) lights simply do not work as well as the traditional HPS (high pressure sodium) or Tungsten Halide lamps when growing large plants. The truth is that this belief is centered around the fact that most of the commercially available LED fixtures are built with low-power cascade LEDs that simply do not give your plants enough light intensity to grow properly. The fact that people do not know how to distinguish one from the other, coupled with the problems of getting a genuine, high power LED lamp makes the use of LED fixtures in hydroponics limited and almost never considered a serious option for modern growers. On today's post I want to talk a little bit about how you can build your OWN high power LED lamp and how this way you can get a cheap, low-energy, highly-efficient device to make your plants grow.

The first thing you need to consider here is the amount of LEDs you will be using (the amount you will require for your plants) and the power supply you will need to feed those little hungry fellows. From my experience I can tell you that the lumens measurement of high power LEDs does not give you an accurate estimation of how many you need since LEDs have a highly centered light spectrum that is more accurately measure in micro Einsteins (the appropiate measurement unit for these devices). In this case I advice an empirical measurement of 5, 3W high power LEDs for each plant you wish to grow and 1 blue LED for every 10 red LEDs. (below you can see a picture of one of my LEDs, the LED was dimmed to get a better picture)
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The second thing you want to do is buy the LEDs, just google red or blue 3W high power LED on ebay and you will find several chinese or US providers who will sell you these great artifacts for a small price. When you get your LEDs make sure you buy at least 3-5 more than what you will need since these LEDs are sensitive and they will burn easily if you wire them incorrectly. Since the power requirements of these LEDs are also pretty high they will get VERY hot (however much cooler than traditional lamps) and they will need to be mounted on aluminimum rails with at least one 6 inch fan for each 5 LEDs (or a BIG rail than can dissipate all the heat).

The next part - which is the most difficult - is the building of the power supply and voltage regulator side of the device. You can use a laptop supply to power up some LEDs but you need to calculate their power requirements so that you know how many you can power up for the power supply you will be using. A very good guide I used to create my LED assembly can be found here. Of course you should change the setup and LED number to fit your needs but the tutorial shows you exactly how you can choose the power supply, calculate LED needs and build the voltage regulator with a simple electronic circuit.
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Finally, after I finished I hooked the power supply of my LEDs to a regular appliance timer which sets them on and off at certain times of the day. Making sure that my basil plants get enough light for their growth even when I am not at home. It is very worth noting that before I installed this LED fixture my basil plants were extremely leggy, etiolated and just dying. A few days after the LEDs where in place they started to grow like crazy :o) Do you have any questions, comments or suggestions ? Have you also built your own LED fixture ? Leave a comment below !

A Simple Home-Made PVC Hydroponic Growing System

2010-06-06T04:22:00.000-07:00

When I moved into my new apartment I wanted to build a small hydroponic system I could use to grow basil just next to a window. Since I absolutely love to cook Italian food and fresh basil is a key ingredient this seemed like the best solution to enjoy my cooking to its fullest and practice the building of a new hydroponic system. I finally decided to build a very cheap and simple PVC system which currently hosts 6 beautiful basil plants that give me more than enough basil for all the Italian cooking I could possibly want. On todays post I want to share my system's design and description with you as well as some picture of my basil plants, showing you how they are doing under this great - yet very simple - PVC hydroponic growing system.

The system I built can be classified as a continuous Ebb and Flow system. It basically has a 2 inch PVC pipe with a horizontal cut on top, a reservoir, an air pump, a water pump and a 1 inch PVC framework that also acts as a secondary reservoir for the nutrient solution. The system is filled with river bed gravel as a growing media and it can be used for the growth of almost any type of plant. Of course, any rocky media that easily allows nutrient solution flow can be used and a larger pipe diameter can be used to grow other plants such as tomatoes, cucumbers, etc. For larger plants a 4 inch diameter PVC pipe and a 2 inch frame work would be required. A diagram of the system is shown below (sorry for the poor drawing skills ;o) ).
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As you can see, the pump constantly sends solution from the reservoir below to the gravel bed inside the 2 inch PVC pipe located above it. The solution recirculates and goes down to reenter the reservoir. Even though the actual passage of the solution may seem "biased" towards once side, the truth is that a small part of the solution actually flows through the whole pipe and ends up draining through the other side as I have not noticed any difference in development between plants in opposite sides of the tube. Since there is a level that has to be filled within the tube before a return of solution is established there is a constant feeding of aerated solution for the plants.

This system is very cheap to build and it can be made with 6 - 90º elbow joints, 3 - T joints, 2- 2' to 1' adapters, 5 feet of 2 inch PVC piping and about 10-15 feet of 1 inch PVC piping. You also need a container that can hold enough nutrient solution volume, a water pump and an air pump. The system provides very good growing conditions for plants and the gravel media provides adequate support for a wide host of vegatable varieties. This system is also great for strawberries and similar crops. Several improvement over this design are obviously possible and many will be featured on future blog post articles as I implement and test them.
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The above picture shows you my setup with the basil plants currently growing vigurously (they are currently about 60 centimeters high). Above the system you can have a small look at the high power LED fixture I built myself to provide these plants enough light (as hardly any light gets through the window). I hope you have enjoyed this article and decide to build your own simple home-made PVC hydroponic growing system. Make sure you leave any comments with questions or suggestions you may have :o).

Understanding pH in Hydroponics - Part No.2

2010-06-04T04:21:00.001-07:00

Yesterday - on the first part of this article - we talked about the nature of pH, the origin of pH changes in hydroponics growing and why these changes happen with time within a hydroponic culture, I also talked a little bit about how to prevent pH changes by building a balanced solution with a given percentage of nitrogen given as ammonium. On the second part of this article I am going to talk about the adaptation of plants against pH changes, why certain pH levels are needed and why there is an important over-focus on the importance of pH which does not need to be maintained in ranges as narrow as most growers believe.

What is the ideal range of pH for plant growth ? The fact is that plants can grow ideally from a pH of 5.5 to about 7.0. Above or below these values certain changes start to happen within the chemistry of the solution that makes nutrients less available to the plant. The large importance of adequate - yet not excessive - control of pH values is to maintain an optimum absorption of nutrients for your plants. When we go below a pH of 5.5 certain nutrients like iron become very readily available while nutrients like phosphorous and nitrogen become much less available. This lack of availability has two main causes. The first one is the overall change of chemical species within the solution, with the newly generated species being difficult or impossible to assimilate by the plant while the second one is that species that become extremely available generate a strong antagonic effect against some nutrients. For example, iron is antagonic with phosphorous and with a pH decrease below 5, the absoprtion of iron becomes extremely easy and therefore the aborption of P becomes more difficult, the overall formation of acid phosphate species which are also not so readily available by the plant further reduces P availability. An image shown below gives you a good idea of the availability of nutrients for plant growth as pH changes.
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However most growers tend to believe that the pH level of their nutrient solution is the pH level that plants have around their roots, something which is actually not correct in the sense that plants have evolved local pH adaptation mechanisms to survive to changes in soil pH. When you measure the pH of your nutrient solution you are measuring the pH of the "bulk" while the pH of the actual root-zone of your plants might be within the ideal zone for nutrient absoprtion. Therefore growers usually underestimate the actual capacity of their plants to correct pH and spend an enormous amount of time tinkering with pH to make it "ideal".

The fact here is that plants do not like abrupt pH changes like those that happen when you add pH up/down to continuously adjust your nutrient solution's pH levels. Plants can deal perfectly with a slow pH increase caused by nutrient absorption from 5.5 to 6.5 but when you - in a matter of seconds - revert the pH back from 6.5 to 5.5 in a matter of seconds you are causing your plants significant levels of stress since they are simply not used within their natural environment to such quick pH changes.

The easiest way I have found to deal with pH is to simply not obsess with it. Most solutions that are well balanced and contain about 10-15% of the nitrogen as ammonium and about 20-40 ppm of phosphorous will adequately contain pH within the 5.5 to 7 pH region from the beginning of your nutrient cycle to the time when the nutrient solution has to be changed. As a matter of fact - beyond the initial adjustment - the changing of pH can be avoided if the nutrient solution is adequately formulated and given in a quantity of at least one gallon per plant. Plants develop well around these pH levels and the improvement you gain from obsessing about perfect pH zone levels will be lost by the stress you put into your plant roots with pH corrections. Of course, there are easy and almost perfect solutions to pH control like the method using ion exchange resins I mentioned in a previous post. A method that mimics the way in which pH is naturally buffered within soil.

Therefore if you want to have a great hydroponic crop with little maintenance and a very good yield I would advice you to prepare your own nutrients taking pH-self balancing and adequate nutrient ratios into account. Certainly this method will give you a lot of control over your composition and a great saving in solution costs.

I hope that after reading these two posts on pH in hydroponics you have now grown a much better understanding of how pH is, how it works and how it evolves in a hydroponic culture. It is very important for you to understand that pH plays a vital role in nutrient absorption but that obsessing with strict pH zones is not beneficial for your plants in the sense that constant additions that cause quick changes in pH values cause stress to their root zone. Adequate nutrient design and a good understanding of how nutrient interact is therefore important for the correct use and low maintenance of a hydroponic crop.

Understanding pH in Hydroponics - Part No.1

2010-06-03T02:00:00.000-07:00

When water reacts with itself to create the H3O(+)(hydroxyl) and OH(-) (hydroxide) species, one of the most fundamental and important characteristics of aqueous solutions is generated. The reactivity of a solution and its interaction with living organisms is determined in a great extent by the concentration of these two species, a variable usually measured as pH which is nothing but the negative value of the logarithm of the concentration of the H3O(+) ion. In hydroponic culture - where our plants are in great contact with aqueous solutions - the understanding of the role of the H3O(+) and OH(-) ions and their measurement as pH becomes very important if an in-depth understanding of what is going on wants to be attained. On today's post I will attempt to guide you into this micro world of pH and how and why pH changes within a hydroponic crop. Tomorrow -on Part No.2 - I will try to explain to you how plants adapt to pH changes and what a pH change actually means for a living organism.

What determines pH ? This variable is inversely proportional to the concentration of H3O(+) ions and directly proportional to OH(-) ions, the more hydroxil ions you have the more acidic your solution will be (the lower the pH) while more hydroxide ions will increase your pH and give you a higher pH reading. It is important to understand here that hydroxyl and hydroxide ions determine each other's concentration. Since water's self-reaction equilibria must be maintained, the sum of pH and pOH must always be equal to 14 (a neat consequence of chemical equilibrium theory). When the concentration of hydroxyl and hydroxide ions is equal, pH and pOH contribute equally to the solution and they are therefore both 7, reason why the pH of a neutral solution has this value.

Now that we know a little bit about pH we can understand better what happens when plants interact with a nutrient solution. When a plant is put within a given solution it wants to absorb the nutrients it needs to grow. These nutrients are avilable as ions that have a given charge. For example, nitrogen is absorbed as the nitrate ion (NO3(-)) while potassium is absorbed as the K(+) ion. When a plant takes potassium in, it deplets the solution of a positive charge. Since the solution must remain neutral the plant gives the solution an H3O(+) ion to compensate. The plant has therefore decreased the pH of the solution by absorbing a potassium ion. When nitrate is absorbed - an ion with a negative charge- the plant does the opposite and exchanges the nitrate for an OH(-), the pH of the solution is increased.
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If plants absorbed nutrients in a perfectly symmetrical fashion, they would not increase or decrease pH as overall charge changes would be compensated. However - as no one is perfect- plants absorb nutrients at different rates and they therefore create a "pull" towards a certain pH region. If a plant absorbs nitrate heavily it will start to contribute far more OH(-) than H3O(+) ions into the solution and the result will be a net increase in pH. Depending on the composition of the nutrients and the overall growth stage of the plant, different net movements in pH can be achieved by the plant.

The most influential factor in the changes of pH within a solution is generally the composition of the nitrogen component of the solution. When plants absorb ammonium ions NH4(+) they tend to decrease pH while nitrate - as mentioned above - tends to increase pH when absorbed. If you contribute a percentage of the nitrogen in your solution as ammonia the net effect will be a beneficial "absorption pH buffer" since plants will take nitrogen in both forms, effectively delaying the onset of important pH variations. Of course, the ratio of nutrients also performs a vital role since plants' nutrient absorption mechanism are largely non-specific and they are greatly influenced by the different concentrations of nutrients within the solutions. Having a nutrient solution designed to provide an adequate balance will be vital in helping you control pH fluctuations.

On part two of this "understanding pH in Hydroponics" post I will talk about the range of pH plants can live in, how they adapt to changes in pH and other interesting aspects that will help you better understand the role and true importance of pH within a hydroponic crop. I hope that today you have acquired a rough idea of what pH represents, the nature of pH changes and some basic things that can be done to improve the pH balance within your hydroponic culture.

Growing a Hydroponic Garden Without a pH or EC meter

2010-06-02T05:16:00.000-07:00

So you have decided you want to start a hydroponic garden but you do not want to use a pH or an EC meter. It is fairly common for people to feel this way when they are starting their own hydroponic gardening due to several reasons. Maybe you are not very familiar with the technical side of hydroponics, you don't want to get into all that stuff in the beggining or perhaps pH/EC meters are terribly hard to get or expensive where you live. Does this mean that without a pH and EC meter you won't be able to run a successful hydroponic venture ? No. On today's post I am going to talk to you about how you can grow hydroponic crops without a pH or EC meter and yet get good results, sometimes even better than people using all those technical gizmos :o).

As a chemist I think like a scientist and part of this way of thinking is the controlling of variables. I like to control pH and EC because I feel that this allows me to have a record of what is happening within my nutrient solution, without these measurements I would be "blind", so to speak. However when I was beginning my major I started my first hydroponic ventures with absolutely no control over pH or EC. I didn't do this because the cost of an EC/pH meter where I lived was prohibitive so I said, "what the hell" and went for it. I have to say that I got some very satisfying tomato crops after having some significant failures due to both rookie mistakes and disease. I managed to get full, 2 meter high tomato plants filled with delicious vibrant tomatoes and this happened without ever checking my pH or EC.

How did I manage to do this ? After time went by and I got an EC/pH meter, I started to monitor how my crop evolved with time to know what I should or should not do to improve my corp's yields. I found out that the pH of my crop increased steadily - and sometimes came near 8 - before I usually changed my nutrient solution. The EC oscillated widely but my reposition of the initial "level" of solution with water was enough to keep the EC at a good level. So if you want to be successful with hydroponic crops, it is not absolutely vital for you to have a pH or an EC meter, you just need to follow some simple guidelines to have a wonderful hydroponic crop.

1. Have one gallon of nutrient solution per plant. Having this volume of solution in your reservoir per plants allows you to have enough nutrients so that each plant will take a significant amount of time to absorb them. Having less solution is troublesome since your EC will change wildly and your nutrient solution changes will have to be more frequent. A one gallon per plant rule of thumb seems to be the best choice.

2. Add fresh water to recover the initial level of your solution . This is one of the easiest things to do. By adding fresh water -without any nutrients- to top off your reservoir to its initial level you will keep the EC near its initial value for the whole time. This simple technique ensures that your EC remains within rational levels and your plants stress-free.

3. Change your solution every 4 weeks. After 4 weeks, in a hydroponics system where there is one gallon per plant and the solution is continuously topped off (at least once a day) you will find that your plants have used about 40% of the nutrients at most (this is what I got from full production tomato plants and an atomic emission analysis of the nutrient solution). This means that your solution is now deprived of nutrients and it is time to use the solution to water your soil-garden and prepare everything again.

With this simple guidelines, anyone will be able to grow a hydroponic garden without using a pH or an EC meter. Of course, in the beginning you may find some problems while you find the adequate level of nutrients your plants need (if you do not prepare them yourself) but after a few trial and error runs you will be able to grow full hydroponics gardens without having to constantly monitor either pH or EC. Certainly, better results are achievable when you are monitoring these variables but it is possible to grow a beautiful hydroponics crop without the slightest monitoring of these aspects of a hydroponic nutrient solutions. People usually underestimate the ability of plants to adapt to changing conditions, something that they are able to do beautifully if you only follow the above advice. Do you have any advice or suggestions to help people grow without an EC or pH meter ? Feel free to leave a comment :o)

Is OceanGrown Fertilizer a Scam ? A Scientist's Point of View

2010-05-26T11:55:00.000-07:00

In recent days I was contacted by a person who wanted to start selling the OceanGrow fertilizer who asked me to be the head of a research team to do scientific tests to evaluate if there is actually any value behind the OceanGrown fertilizer. After going through its webpage and doing and in-depth review of scientific literature on the subject I have acquired quite a lot of information about this fertilizer and its real potential as an organic solution and replacement for traditional fertilizers. On today's post I want to discuss this fertilizer, which is supposed to be used on either soil or hydroponics, and give you my opinion as a scientist and what the currently available scientific evidence tells us about the effectiveness of this and similar products.

The OceanGrown fertilizer is nothing more than sea water which has been concentrated - probably using reverse osmosis - to give us a fertilizer that is supposed to replenish the minerals lost in soil and provide plants with 90 elements for their adequate and healthy growth. The website has an overall pseudo scientific tone with absolutely no reliable scientific evidence shown and basing all conclusion on "facts" that have not been scientifically proved. For example, the website says that elements in sea water are in "ideal concentrations" when this has no scientific basis, no one has proved that certain nutrient concentrations are ideal and no study has actually been conducted to see if the concentrations of micro nutrients on sea water are ideal for plant growth.
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Besides this, the people at OceanGrown assume that having all elements is "good" when actually even small amounts of mercury, lead, cadmium and other heavy metals can cause chronic effects when eaten continuously. They also show evidence that the elements are absorbed by the plants fed with their product something which is absolutely obvious given the fact that ionic species are absorbed by plants since their absorption mechanisms are not extremely controlled. Does the fact that a plant absorb aluminium or gold prove that the element is essential ? No, plants absorb ionic species without too much selectivity and when you feed a plant with a solution containing non-essential nutrients the plant is bound to absorb some. This effect is widely studied in science to remove heavy metal contamination and other ionic species using plants. There is no scientific evidence that points out that any elements besides C, H, O, N, P, K, Mg, Ca, Fe, Zn, Mn, Cl, Mo, B, S and Cu are essential to plant life or needed for the adequate and healthy development of plants.

The "essays" carried out to test this fertilizer's efficiency also lack any use of the scientific method and fail to discard very plausible causes of this fertilizer's sometimes positive effects. For example, increases in conductivity have been found to improve certain crops in hydroponic culture so the effect of this fertilizer might only be of ionic strength increasing which might help certain crops achieve better results. It is also possible that some micro nutrients - which are depleted in soil - might be added by this fertilizer but in the long term the excessive amount of sodium and chloride ions contained in sea water is bound to cause problems. The evidence that increased sodium concentrations in hydroponic crops causes damage to plants is a well established fact in the scientific community.

The people at OceanGrown seem to be trying to sell a fertilizer with extremely limited and lack of adequately confirmed evidence based on a series of pseudo scientific facts that are not adequately backed up by our current understanding of how plants work. This fertilizer might be able to work to some extent but the reasons why it does or if it causes any long term problems and damage to soil needs to be addressed to confirm the viability of this solution. Right now there is not even one single study published on a peer-reviewed scientific journal that talks about the effectiveness of OceanGrown or true scientific essays done with this solution. It seems evident to me that similar effects as the ones shown by this fertilizer might be achieved by a simple application of an adequately formulated micro-nutrient mix and that positive effects from all the trace elements found in sea water might be limited or undetectable at best.

In conclusion, I think that the OceanGrown fertilizer is a big business based on selling sea water that is currently based in pseudo scientific results. There is no evidence that plants need or benefit from 90 different elements and there is also no evidence that shows that this fertilizer has no long term ill effects due to the excessive sodium enrichment of soil. If this people were truly serious about proving that their fertilizer works in a unique way based on all of its trace elements they would have made adequate scientific trials years ago with reputable scientists from world renowned universities. My advice if you are thinking about using this solution would be to use what we know and have determined works for plants. The application of adequately formulated micro nutrient blends and full fertilizers is a much better solution than a pseudo scientific mess with no adequate scientific evidence of unique results.

Of course I am a scientist and as soon as there is a peer reviewed publication on a well-respected journal done by an unbiased researcher I will be the first to reexamine my conclusions and use this fertilizer. Meanwhile OceanGrow remains unproved and their claims or at least their explanations, remain pseudo scientific.

Fruit Quality and High EC values in Tomatoes

2010-05-24T11:06:00.000-07:00

You may remember an article I wrote last year about the effect of salt concentration in tomatoes and how several different studies have been done about this matter. On that article I talked about a paper released in 2007 showing that tomatoes raised at an electrical conductivity value of 4.5 dS/m had the best tasting and fruit quality. However, this study was not conclusive in the sense that quality parameters used on the plants where not extensive and adequately analyzed. On today's post I want to talk to you about a previous study done in 2006 which does include fruit quality parameters and a clear explanation about which conductivity levels give you the best tomatoes and why this is the case.

The relantionship between high conductivity and high fruit quality clearly depends on how you evaluate fruit quality. In general, the nutritional quality of a fruit is measured by the concentration of important nutrients within it. In the case of tomatoes, important nutrients such as lycopene, vitamin C, carotenoids and phenolics determine most of the tomato's nutritional value. However, fruit quality - from a market perspective - relates to size, shape, uniformity and firmness and market duration.
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On a study published on the Journal of Agricultural and Food Chemistry in 2006, Woitke et al discussed the effect of electrical conductivity on the yield and quality of tomato crops. Their conclusions after analyzing the concentration of several nutrients at different salinity levels was clear : tomato crops which are raised at higher EC levels have lower overall yield but the concentration of nutrients (vitamin C, lycopene and beta-carotene) was increased by as much as 38% on high conductivity treatments (again at about 4-4.5 dS/m). They also found a nutrient-quality increase as the antioxidative capacity of the phenols and carotenoids increased on the plants with high nutrient treatments.

Another very important fact is that not only nutritional value was increased but total dissolved solids and organic acids - which contribute significantly to the fruit's flavor - also increased significantly. Overall the study concludes that all quality related parameters increased with the increase in salinity pointing out clearly that raising tomatoes at high salinity levels is an excellent way to increase fruit quality. The reduction of yield can be compensated for by the higher inner quality of the fruit allowing it to compete more effectively with other higher-yielding yet lower quality productions within the market.

So next time you want to increase the taste and nutritional qualities of your tomatoes just raise your EC levels so that your fruits accumulate the higher levels of nutrients and flavor producing substances that reside within every small tomato. Certainly your tomatos will be the envy of all other growers with their higher nutrient and flavor levels and increased antioxidative capacity.

The Best Outdoor Hydroponic System. A Simple Way to Grow Large Amounts of Food

2010-05-23T10:31:00.001-07:00

I have always seen that there is not a lot of information regarding outdoor hydroponics and the building of scalable and cheap systems that may provide large amounts of food without the complexity, trouble and expense of building a greenhouse. For the past several years I have been puzzled by this issue and I have challenged myself to build an outside hydroponics system that is able to deal with environmental conditions successfuly, providing adequate conditions for plant growth without significant expenses and without the need for any protective enclosure. Finally, I came up with a system which - I believe - has a lot of promise for the above, giving us the opportunity to build an outdoor hydroponic system which has a low cost and a very high productivity potential. On today's post I will be talking about this system and how it can be easily built with less than 1K USD for each 100 square meters.

How do you build a scalable system that can be used on the outdoors with minimal problems due to uncontrolled environmental conditions ? The easiest thing I could think of was a simple continuous flow system which used the ground itself as a place to put the plants. This system uses no NFT channels, no large amounts of PVC pipes and absolutely no complex engineering. The system - shown on the drawing below - is simply a channel which is dug on the ground of about 2 meters wide by 25 cm deep. The nutrient reservoir can be a tank burried in the ground or a reservoir made from bricks and tiles out of another hole dug on the ground depending on the actual volume needs of the crop. The hydroponic system uses a PVC line connected to a pump to irrigate the system at the top and a small decline in the slope of the channel allows the solution to return to the tank through an underground pipe shown in dark blue. The channel is filled with a nutrient media that has adequate drainage and the nutrient solution is fed continuously through the irrigation system. Of course, when the channel is dug on the ground the soil has to be covered with a polyethylene sheet to prevent the solution to drain into the soil.
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This system allows you to grow a wide variety of crops, from tomatoes to lettuce heads. The system can be used to grow plants of various sizes and nutritional needs since the media and continuous flow irrigation provides great oxygenation as well as a cheap alternative to more complex systems such as NFT or PVC pipe systems. The system is also absolutely scalable, it can be built from a few square meters to a full plot size commercial cultivation facility without significantly changing the principle of operation. Since the surface area of the system is also large, and all nutrient solution is returned to a central reservoir, rain volume can be accurately determined and nutrients can be added or changed to make up for this effect of external environmental conditions.

The image shown below shows you how the system can be expanded to a full plot system without any modification of the fundamental working principle. The only things that need to be bought to start this system are a tank, a shovel, a polyethylene sheet as large as the channel requires, PVC pipes for the irrigation system and returns pipes, media, nutrients and seed. Since there is no greenhouse, no gutters, no polymer channels and no expensive irrigation equipment, the system is very simple and effective at growing plants at a large or small scale under outdoor conditions. It is also perfect for people who want to start a small hydroponic business and then expand it as they want to increase their production, since adding channels is easy and requires almost no changes (besides perhaps having larger pumps and increasing reservoir size once this is required).
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In the end I believe that this system summarizes everything that I wanted to achieve with an outdoor hydroponic system. It is able to control and measure the effect and added volume of rain, allows the growth of a large variety of plants and provides us with a cheap and scalable solution to small and large scale commercial growing. Definitely there will be some problems that will probably have to be solved once larger applications start to develop but certainly I can say right now that this idea seems to be the largest, cheapest and most scalable solution for outdoor hydroponic growing available online :o).

Crazy pH Swings - How Media and Bacteria Affect pH in Hydroponics

2010-05-21T07:39:00.000-07:00

I usually get an email from time to time from someone who is experiencing wild pH swings in their hydroponic reservoirs. Growers usually tell me that their pH was around 6.2 one day and then 8.0 by the next morning or some similar story. This situation becomes a little bit frustrating as the grower does a huge effort to keep the solution at a certain pH level only to realize that after a certain time the pH of the solution simply starts to swing wildly between very odd values. In order to help new and experienced growers better understand the nature of these swings, what they mean, and how they can be eliminated for good I decided to write this small article on hydroponic pH swings and how variables different to plant feeding affect pH levels.

Let's suppose you got home from work, prepared a new batch of nutrient solution and set your pH level at a very comfortable level of 5.7. By the next day, when you wake up in the morning to check your plants you find that the pH of your solution is 7.5. You start to argue with your pH meter, recalibrate, readjust your solution and leave for work. When you come back - to your surprise - your pH level is now around 7.3. What ? - you ask yourself - What could be wrong if you set the pH to 5.7 again and it again went up to 7.3 ?
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The answer to these wild pH swings comes from an understanding of the chemistry behind everything within your hydroponic system. Generally these swings towards high pH values are caused by media which has surface-active basic sites which act like "buffers" and readjust the pH of your nutrient solution to their own "preset" pH level. This is very much like the mechanism used by soils to naturally control pH, only that this time the minerals are playing against you. Substrates that have been made at high temperatures which have basic potential - such as rockwool - show this kind of behavior. Other media such as river bed gravel also show strong pH buffering effects due to their natural mineral composition.

How do you end this problem ? The easiest way to end this problem is to pretreat your media before starting your crop. Place your media in a bucket and then add 1 liter of vinegar for every gallon of water. The media will attempt to neutralize the acetic acid and in doing so it will lose the proton capturing ability of its surface basic sites. Using a weak acid like acetic acid is better than using a strong acid - like nitric acid - because this ensures that residual acids within the media won't lead to other extreme pH fluctuations. After the media is soaked in the vinegar solution measure the pH, wait a day and measure it again. If there is no difference between both readings then you can now wash and use the media - if there is - then you need to wait another day and remeasure.

Now basic media is not the only problem around. There are also wild swings to acid values which are usually a consequence of bacterial growth or dying organic matter. When organisms die or when they are being decomposed by bacteria organic acids - which lower pH - are released into your nutrient solution. Wild swings into the 3.5-4.5 region usually mean that the problem is not media but related to root disease. You should do a hydrogen peroxide treatment (check my articles on peroxide for more on this) and wait to see if pH levels stabilize after a while. In extreme cases, physical removal of dead root material may be necessary to correct the problem.

Last but not least, the problem can also be related with plant feeding from a very scarse volume of solution. If you are handling less than 1 gallon per plant of solution in your reservoir then it is likely that plants themselves - through the absorption of nutrients - are causing the swings. This is easily fixed by placing a larger reservoir and ensuring that you are always recirculating at least 1 gallon per plant of nutrient solution. Hopefully with the above guide you will be able to better understand "wild" pH swings and take corrective action whenver you see this behavior happening within your hydroponic crop.

Preparing your Own Chelates - Improving Your Hydroponic Nutrients

2010-05-20T08:49:00.000-07:00

If you have already read my free ebook for preparing hydroponic solutions and you have already seen many commercial and other standard formulations you may be asking yourself if you will have problems with iron due to the unavailability of any chelating agents. The truth is that I have used formulations without any chelating agents several times and I haven't had any problems when they are prepared by the ebook. However many of you may be interested in the addition of chelating agents and you may wondering how you may modify the spreadsheet or what you should add in order to generate the adequate chelates. On this post I want to explain a little bit how you can add chelating agents to your reservoir to chelate the salts mentioned on my ebook and how this can easily generate all the chelated metal complexes you need to avoid any solubility problems.

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What is exactly a chelate and what are they good for ? A chelate is simply an organic molecule that "wraps" itself around a metal ion and prevents its precipitation, increasing its solubility. Chelates also diminish the amount of available metal ions to plants and therefore they slowly release the quantities of micro nutrients available for plant growth. There are many available pre-made chelates on the market such as Fe-EDTA. However, the cheapest way to generate chelates once you already have a standarized formulation based on simple inorganic salts is to add a chelating agent.

The most common of these agents is called Ethylendiamintetraacetic Acid (EDTA), a tetraprotic acid which is able to chelate most metals with a particularly high afinity for Fe. However, when you add only chelated iron, the fact that other metals start to compete makes the iron complex destabilize and the chelate is eventually destroyed. However, when we add the chelating agent we can make sure that we add enough to "wrap" Fe and other metals in such a way that the stability of the iron complex is guaranteed.

When we add the chelating agent we do not add EDTA (the acidic form) but we add it as a salt of another element, usually K-EDTA. Once this is added to the solution the EDTA quickly gets rid of K and goes for another metal - such as Fe - for which it has a much higher affinity. The chelating agent quickly forms complexes with all the metals it loves and you end up with a solution that is highly stable and not prone to any micro nutrient related precipiation. How much do you need to add ? Depends on your formulation. The spreadsheet download with the ebook shows the amount of chelating agent (K-EDTA) you need to add to the END solution after all micro nutrient concentrated solution additions have been done (this amount fully complexes Fe, Mn, Zn and Cu).

Urea in Hydroponics - Positive or Negative ?

2010-05-20T08:15:00.000-07:00

When we supply nitrogen in our hydroponic solutions there are always a several ways in which we can fulfill our plants' needs for this nutrient. The traditional way is to supply nitrogen solely as nitrate (NO3-) salts, something which is well proven to give good results, high yield crops and better than soil growth. However it is always good to ask if a combination or the use of additional nitrogen sources may improve the outcome of our hydroponic experience. Particularly since plants in soil absorb nitrogen as nitrate and ammonia it becomes worth asking if a slow releasing source of ammonia- such as urea - would improve the yields of our hydroponic system. On this post I will write a little bit about the use of urea in hydroponics and the scientific evidence that there is to support or reject its use.

Urea is an organic molecule which slowly decomposes in water to yield ammonia and carbon dioxide. If the media is slightly acidic, the ammonia released will get protonated to form ammonium, a form of nitrogen which can be readily assimilated by most plants. Moreover, this form of nitrogen can also be processed by bacteria to yield nitrate, providing us with an additonal - slow release- mechanism for nitrate supplementation. Several research groups have asked themselves if urea would bring any significant benefits to hydroponics crops. Of particular interest was a study published by Oda et al, dealing with the effects of Urea and nitrate fertilization in hydroponics crops using both organic (peatmoss and baggasse), inorganic (rockwoll and sand) media and pure NFT systems.
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After doing a study with several concentrations of Urea and Nitrate -both by themselves and combined - this research group found out that Urea does not improve crop yields in NFT systems and indeed pure nitrate does the best job when no media is in place. When media is introduced, organic media shows a faster Urea to Ammonia conversion but Ammonia to nitrate conversions are faster in inorganic media. However, the effect of Urea remains poor in the sense that nitrate-only crops outperformed almost all crops except for some plants grown with small quantities of Urea which proves to be beneficial in the same way as small additions of ammonia are already known to be.

So in the end, is it worth to add Urea to a hydroponic formulation ? The scientific evidence says that Urea does not have any clear beneficial effect that could not be gained by a small addition of ammonium salts, something which has already been confirmed by several studies done on different plant species. If you are planning on starting a new hydroponics crop adding about 5-10% of your total nitrogen as ammonium may prove to be beneficial but any addition of Urea seems completely unecessary.

Of course, further research on this subject would be needed to know the effect of nitrate/ammonium/urea combinations to know if the beneficial effects are a sole consequence of the presence of small quantities of ammonia or a virtue of the "regulatory" effects introduced by Urea as a slow release ammonium fertilizer.

Hydroponic Tomato Formulations - Nutrients for Every Growth Stage

2010-05-20T07:50:00.000-07:00

One of the most interesting things that can be done once you know how to prepare your own hydroponic nutrients (check out my free ebook on the right hand menu) is to make formulations for the different growth stages of your crops. Certainly the variation of several nutrients along the different stages of a plant's life will guarantee optimal production with better than average results. In the beginning it certainly isn't very clear how you should vary nutrients and careful care about the amounts - particularly the ratios between nutrients - have to be taken into account in order to have the best possible results. On today's post I want to talk a little bit about hydroponic tomatoes and how we can design a very specific "feeding schedule" with small modifications in our nutrient formulations for the whole growing process of this plant.

When you are growing plants, their needs are obviously not the same along all their growing stages. In a similar way as a 5 year old human doesn't need the same nutrients as a 16 or 52 year old, plants that are just germinating and plants that have been flowering or have just begun their fruiting have different nutritional needs. In tomatos, these differences manifest themselves as different demands for the different nutrients. For example, demand for magnesium, nitrogen and potassium increases as the plant grows older as more nutrients are needed to develop more live material. However some needs - such as those of micronutrients - remain fairly constant as the demand for most of these ions is not increased radically as the plant grows.
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Of partiular usefulness to understand how to improve your tomato crop by developing a formulation schedule is a study done by the university of Florida by Hochmuth et al. The study shows the design and application of a feeding schedule to tomato crops from transplant to fifth cluster development, changing nutritional input as the plant develops. You can access this study here and look at all the different formulations developed for different stages of tomato growth. By using the ppm values provided on this study you can easily prepare nutrient solutions using the spreadsheet provided with my nutrient preparation ebook (available freely).

When you analyze the nutritional formula given above you can see how some nutrients are increased gradually while some are increased in large steps. You can also see how some ratios - like the N/K and Ca/K relationships - vital to the development of healthy tomato fruits, develop as the plants reach a more mature stage. In the beginning, small quantities of nitrogen (< 70 ppm) are available while in the end this quantity is increased to 150 ppm falling in line with the demand of a much larger fruit-producing plant.

Hopefully with the above guidance and reasearch article you will be able to start some customized nutrient scheduling for your tomato crops to improve their yields, making sure that your plants get the most out of the nutrient formulations they are using.

How to Have a Constant pH in Hydroponics - No More Corrections ! :o)

2010-05-20T03:40:00.000-07:00

Those of you who have read my other articles or all of you who have already had your first hydroponic crop know that pH is a constant concern which becomes a little bit of a pain after a while. Hydroponic gardeners need to constantly adjust the pH of their hydroponic solutions to the desired level and - although many are really obssesive about this - it is truly not very comfortable to have to do these corrections day in and day out. So how do we completely avoid the need to modify the pH of our hydroponic crop ? How can we maintain the pH of our crop constant as time evolves ? Through this article I will show you what I have found out - both through personal research and an extensive literature search - and you will see that there is a very EASY solution to maintain the pH of your hydroponic solution with NO further modifications.

So how do you maintain pH constant ? There are several ways to tackle this problem. The use of a citrate/buffer has been discussed on a previous article but its use is affected by the fact that calcium citrate is insoluble and nutrient solution composition limits the concentration and effectiveness of the buffer to around 1mM. Carbonate ions also pose a problem since their concentration also needs to be kept at a safe thresehold for the plants which is also around the 1mM level. In the end this buffer is able to control pH to a good extent buts its practical use is limited by calcium levels and the presence of citrate ions may also cause important complexation of ions such as zinc, an effect which - if used excesively - may cause micro nutrient defficiencies.

How do we keep pH constant without using any buffer ? The solution comes as ion exchange resins. These substances are polymer like matrixes which have functional groups on their surface that react with acids and bases and provide you with a constant pH level. Ion exchange resins are insoluble and the only thing they need to be efficient is to have solution passed around them all the time. So it is simply a matter of putting the ion exchange resin in a place where fresh passing solution will be in contact with it all the time - like inside a filter connected to the irrigation system - and thats it, no more pH problems, no more additions to control pH, problem absolutely solved.
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However not ALL ion exchange resins work. Particularly the type of resins that work well in hydroponics are weakly acidic cation exchange resins and their effect has been studied extensively on several peer reviewed publications. If you want to use these resins in your hydroponic system you need to buy the commercially available Amberlite DP-1, Amberlite IRC-50 or the more recently available Amberlite CG50. You would need about 1g per gallon of solution you wish to control and you should place the resin in an inline filter - those used for drip irrigation are great - to achieve the desired pH control levels. When the resin stops working you simply need to take it out, wash it place it in dilute hydrochloric acid (your average pH down solution will do), then wash it again, to regenerate its surface and prepare it for another crop.

If you are wondering where you can buy these resins, sadly DP-1 and IRC-50 have gone out of production but small quantities are usually available on ebay if you want to buy them. Similar resins are also produced by chinese companies right now so if you are into importing you may also explore that option. The easiest resin to get is Ambertlite CG50 which is the weakly acidic resin that replaced the two above, you can buy it from well-known chemical suppliers here and here. They are expensive but they can be renewed almost infinitely (more than 100K times) :o)

I have used these resins with very good success on several hydroponic crops and I can tell you that I haven't added a drop of pH up or down during more than 3 months of growing. When pH fluctuations start to become important I simply take the resin out, regenerate it and put it back in. A very simple process which needs to be done about once every 3-4 months. If you want them to last longer, simply add more resin ! I hope that this article helps all of you who have been dealing with the pH adjustment problem finally get rid of this matter an achieve a new era of success in your hydroponic gardening :o)

The Importance of Oxygen in Hydroponic Systems

2010-05-19T18:06:00.000-07:00

It is very common for new hydroponic gardeners to have an over developed focus on the nutrient aspects of their cultures while totally neglecting other very important aspects such as aeration and light. Some of the most common problems that plants face are a direct consequence of a lack of a proper supply of oxygen, issues which could easily be fixed if this factor was taken into account with as much interest as the composition and character of the hydroponic nutrients used. On today's post I want to talk a little bit about the paramount importance of oxygen, why it is so important and what things you can do to ensure that your hydroponics crops are not starved of this extremely important element.

First of all we need to understand why plants need oxygen. This gas is vital for many living organisms because it performs a very important function within their cells. Oxygen reacts with carbohydrates within any aerobic organism's organelles to produce ATP, which is the primary chemical used to fuel biochemical processes. Plants need this ATP to perform several functions which require energy, like the absorption of nutrients and the production of aminoacids. Plants need great amounts of oxygen in their roots in such an extent that one of the limiting factors of growth in hydroponics - after light - is oxygen availability to root cells.
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A very important thing that you must take into account is how much oxygen your hydroponic system allows roots to have. Static culture systems, like lettuce floating rafts or any system where roots are permanently soaked in water offer little available oxygen since the solubility of oxigen in water is quite low. Even if you aerate the solution constantly using an airpump, the solubility limitation makes the use of such systems to grow large plants - such as tomatoes - extremely difficult.

Larger plants, which have much larger nutrient and energy requirements generally need systems in which the availability of oxygen is not limited. In this case systems where roots are periodically wet and exposed to air have very good results. For example, ebb & flow and drip irrigation systems in which plants are in contact with nutrient solution and with air in an on/off manner guarantee that the large oxygen requirements of energy demanding plants will be fulfilled. In the end, you will see that plants will perform much better when their oxygen and nutrient availability is optimal. For this reason - aeroponic systems - which supply both requirements in an ideal fashion tend to give the best results for most plant types.

In your hydroponic system, ensuring a good supply of oxygen is absolutely vital. You should ensure that your hydroponic system is adequate for the plant you want to grow and you must also check that your system is always giving its maximum oxygenation potential. In static systems you always need to check the frequency and quantity of aerators and on dynamic setups checking cultivation media drainage and irrigation frequency is key to get the best possible results. After taking into account all this you will see that paying close attention to oxygenation will eliminate many of the problems you may have, giving you a much healthier and productive hydroponic crop.

Making Your Own Hydroponic Solutions - Download my Free Ebook

2010-05-19T17:47:00.000-07:00

Many of us have always dreamed about making our own hydroponic solutions to stop buying all those expensive solutions from the hydro fertilizer companies. Sadly, most people do not have the necessary knowledge to prepare solutions and coming up with an adequate formulation seems to be extremely difficult for almost everyone out there. As a chemist, I have the fortune of having the knowledge necessary to prepare hydroponic solutions and the initiative to teach you how to do this by yourselves in an understandable way. Through the past 6 years I have worked as a hydroponic consultant, lecturer and avid gardner and I believe this experience allows me to teach all of you how to design your own hydroponic solutions.

How do you make your own final solutions ? The first thing is to get away from the notion that doing this is extremely difficult. Certainly there are a lot of technical aspects that need to be known but I have taken them all and simplified them so that everyone can actually make their own hydroponic fertilizers with little or no practice. Within my ebook - which you can download freely at the end of this post - you will find detailed instructions on how to prepare your own hydroponic solutions using a spreadsheet I made that makes the preparation of these solutions extremely easy.
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My ebook gives you the ability to take any formulation and easily translate it into the real amounts of chemicals you need to weight in order to prepare your final hydroponic nutrient reservoirs. All the chemicals I have included within the ebook are extremely easy to find - as they are very common fertilizers- allowing you to prepare ANY formulation you may want. You can now fulfill your dreams of preparing one solution for each separate growth stage controlling the exact amount of each single nutrient you add into the solution.

What you will find here is a very easy to use solution - made by a proffesional in chemistry - that will help you prepare fertilizers in the most cost effective yet flexible and satisfying way there is. You will now know exactly was is inside your hydroponic formulations and you will be able to pin-point and solve any nutrient related problems that may arise within your crop. You will also be able to easily discard problems as not being nutrient related since you KNOW the exact quantities of each nutrient you are putting into the solution.

So are you ready to embark yourself in the journey for total freedom and independence in the world of hydroponic nutrient solutions ? You can download my ebook here. Please leave any comments with any suggestions, questions or doubts you may have :o) Also if you want to share this ebook with anyone please direct them to my website so that they can download it themselves.

I have also recently made a great move forward by coding my own windows application to calculate hydroponic nutrient formulations. If you would like to learn more about this program and download it absolutely for FREE please follow the link shown below.
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Hydroponic Nutrients... Why Solid is Better than Liquid

2010-05-19T17:26:00.000-07:00

One of the most important decisions you can make when buying hydroponic nutrients for your plants is the way in which the nutrients are prepared. Fertilizers for soil-less culture are available both within solid and liquid presentations and it is very likely that you have been buying the liquid once up until now since these are the most well-known and easiest to prepare. However, you may not be realizing that by buying liquid fertilizers you are putting an enormous burdden on your hydroponic growth wallet. The fact is that by buying solid hydroponic nutrients you could be saving 5 to 10 times your hydro-food costs. Within today's post I will explain to you the difference between solid and liquid fertilizers and why buying solid nutrients is always a better choice for your hydroponic garden.

Liquid fertilizers available for hydroponics are generally prepared by dissolving an array of salts and additives in water. After these additions are done the concentrated solution is prepared and ready to be sold. When you get it the only thing you need to do is to take a given measure of volume from the liquid and poor it into your hydroponic reservoir. What you may not be realizing is that - due to the fact that salts need to be dissolved in water - there is an inherent limitation in the amount of nutrients you are getting and most of what you are buying is actually water. There is also the added cost that in order to make up a concentrated nutrient solution, compatible salts have to be used. This limits the chemicals that can be purchased and makes the cost of the fertilizer higher.

When you purchase a solid hydroponic fertilizer you simply buy a mixture of salts which you then need to weight and dissolve in a given volume of water. Since there is actually no water and the salts don't need to be predissolved in a concentrated solution, the array of salts that can be used are a lot wider and much cheaper costs can be achieved. Added to that is the fact that packing is a lot simpler and much more efficient since the need to bottle solutions is unecessary. In the end you will see that with 2 pounds of solid nutrients you will be able to prepare more than 300 gallons of nutrient solution while you would probably need much more (about 10-30 gallons of concentrated solution) to prepare the same amount using concentrated liquid fertilizers.
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You will definitely see that most hydroponic fertilizer companies are simply charging you a lot for liquid fertilizers when you could as easily be buying bulk solid fertilizers at a fraction of the cost. Premixed solid hydroponic fertilizers are also widely available commercially and easily made up with some basic chemistry concepts (more on this on a later article!). So next time you are planning to buy more hydroponic fertilizers think about cost efficiency and look for some solid premixed hydroponic nutrients which are bound to give you as good - or better - results than your previous liquid mix.

Hydroponic Solutions and Vitamins... NO real proof

2010-05-19T17:09:00.000-07:00

It has always surprised me that vendors of hydroponic solutions have always included vitamins and other nutrients as a "boost" and "bonus" of their nutrients. It is not very rare to see a fertilizer containing vitams of the B complex, C, E, etc. When I first learned about this practice to include vitamins - as an avid hydroponic gardner and consultant - I decided to look into this and see if there was actually any positive effect or recorded evidence of the effect of adding vitamins into a nutrient solution. On today's post I want to talk a little bit to you about my findings on the subject and the real truth behind the addition of vitamins and other "mysterious" additives into nutrient solutions.

What is a vitamin ? In order to understand the problem we first need to understand what a vitam is. These compounds are usually defined as substances which are not synthetized by an organism - usually humans - and needed in milligram or submilligram doses each day for survival. This means that vitamins are vital nutrients which are not synthetized by the human body but - unlike other chemicals - they are only needed in very small amounts. The reason for this is that vitamins are usually used only as means -not as ends - within our body's biochemistry. So the body uses vitamins as intermediaries for a lot of biochemical processes and only a few vitamin molecules are actually damaged along the way. If a small diary intake is not made to replace the lost soldiers your body will eventually run out of these "messengers" and you will die.
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Why in the world do plants need vitamins ? The truth is that plants don't need vitamins because they are the organisms which produce them. Consuming vitamins is vital to us - humans - because we cannot make them within our bodies. However, the vitamins we eat come naturally from plants or other organisms who have eaten plants as well. So do plants need vitamins ? No, they don't. The question now would be : do plants benefit from the addition of vitamins to their roots and/or leaves ?

The fact is that there is simply absolutely NO scientific evidence published in a peer reviewed journal that points this out to be the case. I carried out an extensive search for any scientific literature that evaluated the effect of vitamins on plants and I came up with nothing. No one has studied this and no one has ever claimed that there is any benefit whatsoever gained from adding vitamins to nutrient solutions. Why do sellers do this then ? The fact seems to be that people buy solutions that have vitamins more, just because we have been educated to believe that vitamins are good. So if they are good for us, then maybe for our plants too.

The truth is that whatever benefit is gained from adding vitamins is not documented or accurately studied by an unbiased third party so up until now there is no scientific evidence to proof that vitamins do anything more than add to the price tag of whatever hydroponic nutrient you are getting. The fact is that as many other substances, vitamins may just be used - either by microorganisms within the solution that cannot produce them - or they may simply decompose as oxygen reacts with them. So next time you are going to buy your nutrients you should ask yourself... Is there really any benefit to this additive ?

Choosing a LED Grow Light for your Hydroponic Crop

2010-05-19T16:45:00.000-07:00

One of the most common problems faced by urban gardeners who want to deal with hydroponic crops is lack of light. Generally plants need very large amounts of light to grow which can only be given by very powerful and expensive lamps which also have the big draw back of consuming large amounts of power. The solution - now readily available - is to buy light emitting diode (LED) lamps to deal with a very efficient yet low consuming light source for your plants. On today's post I want to talk to you about how you can choose your light emitting diode lamp for hydroponic growth and what lamps you should definitely avoid if you don't want your crop not to be a total failure.

So what is so expensive about current lamps and so great about LEDS ? Currently the traditional way to supply artifical light to crops has been the use of full spectrum lamps which can be either tungsten metal halide or high pressure sodium (although sodium lamps have a much narrower spectrum). These lamps are very inefficient - wasting most of the power given to them as heat - and therefore consume great amounts of power. A high pressure sodium lamp (HPS) needs to consume about 400-700W to be able to sustain an average tomato plant. The truth is that most of this energy is wasted as heat and almost none of it (around 20-40W of light) are actually absorbed by the plant.

Here is when LEDS come to save the day. Light emitting diodes are very efficient in generating light from electricity (wasting only a small fraction of the energy as heat) and they also provide light in very narrow ranges which can be tuned to only supply the wavelengths needed by plants. The reason why plants are green is because their main photosensitive pigment is chlorophyll (there are several types by the way), a pigment that absorbs red and blue wavelengths and reflects green. With this in mind - not only are LEDS able to supply your hydroponic plants witha higher efficiency - but they are also able to provide your plant with only the colors of light it needs. Achieving a double gain in efficiency. As a matter of fact, a LED lamp with just 60W is enough to grow a tomato plant.

However, not all LEDS are created equal. Many people think that all LED lamps are the same and they end up buying cheap LED lamps or panels that simply do not provide plants with the energy they need to grow. There are generally two kinds of LEDS available for lamps. The first kind - low power LEDS - are the type of lights used to make your computer and keyboard lights. These lights are weak and they are usually sold in the forms of panels with HUNDREDS to make them appear "useful" for hydroponic growth. The second - high power LEDS - are lights used for traffic lights and high power applications and they ARE the type you need for hydroponic growth.
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In general, when you are looking to replace your TMH or HPS lamps with LEDs you need to look for high power LED lamps in the range of 50-100W for each 400W lamp you want to replace. You also need to look at the red to blue light ratio since different plant varieties need different proportions of light. If you are growing plants that need to have flowers then you will need to aim for a red to blue ratio of about 8:2 while plants that do not produce flowers may grow well with only red lights. This is - of course - a very course guide to the light color ratio but it may guide you well when you are looking for lamps for a certain crop.

With this small guide and knowledge you will be able to eliminate most lamps that do not work and buy high power LED lamps that will deliver and provide you with a much more efficient, cooler and more eco-friendly way to provide your hydroponic crop with artificial light.

Static Hydroponic Systems, Cons and Pros

2009-02-26T03:49:00.000-08:00

There are several systems available today in which hydroponic crops can be grown. All hydroponic systems can be divided into two main categories defined either as static or dynamic systems. In hydroponic dynamic systems the solutions is recirculated at some point by using a water pump while static systems neglect the use of a pump or any other way in which water can be recirculated.

Static hydroponic systems can then be divided into two large categories, open and closed systems. In open systems, the nutrient solution that is given to the plants is never recovered and is "wasted" while in closed systems the solution is used for as long as it has the right chemical properties to feed the plants. For example, a lettuce raft system with no water recirculation is considered a static closed system (since the solution stays in contact with the plant until it is not right anymore) while a drip irrigation system with no pumps is considered an open system because new solution is given to the plants continuously. I will now discuss some of the pros and cons of hydroponic static systems, both open and closed.

Open Static Hydroponic System

The largest advantage of open static hydroponic systems is that the cost and infrastructure needed to pump solution back into the nutrient reservoir is neglected, this cost can be significant if solution volumes are small. Another important advantage is that the concentration of nutrients and pH of the nutrient solution does not need to be checked because fresh solution is continuously provided.

The main drawbacks of this systems have to do with the cost of the nutrient solution spent and the dumping of hydroponic nutrient solution in either soil, rivers, or the sewage system. Hydroponic nutrient solutions are very contaminating because of the easiness with which they cause algae blooms. The solution needs to be correctly processed in order to guarantee no contamination occurs, doing this will most often require water pumps, something which makes the first advantages of these systems void. The cost of the nutrient solution also becomes prohibitive. A regular plant consumes about half a gallon per hour in a drip irrigation system, wasting this amount of solution every hour in a commercial facility is unacceptable (reason why no commercial growers use open static hydroponic systems).

Closed Static Hydroponic System

This systems have the advantage of not being contaminating and using nutrient solutions as effectively as possible. They are the most economical systems that can be built and they provide ideal growing conditions for most plants with short life cycles. Larger plants like tomatoes do not benefit from having their roots wet all the time and require some sort of special design within the system.

The main disadvantages of these systems have to do with the necessity for water oxygenation (using air pumps) and the need for continuous monitoring of the nutrient solution in order to guarantee that ideal conditions are always met. This of course, is not very complicated and can be done with no problems. Most commercial growers will couple the ideal of a static system with a dynamic one in order to further improve it's effectiveness. For example, commercial lettuce raft growers often add water pumps in order to circulate, sterilize and oxygenate the water instead of using air pumps to do this.

As you can see, most static hydroponic systems are pretty primitive and are often confined to small home growers whose concern with efficiency and optimal conditions is not as strict as those of commercial growers. Almost all commercial growers use dynamic systems of some sort and that should also be the aim of home growers as these systems have shown to be more efficient and ecological albeit more expensive than static cultivation methods.(Below, a closed static hydroponic system for herb cultivation)
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Easy Seed Germination with Polyurethane Foam

2009-02-19T18:14:00.000-08:00

Most hydroponic gardeners germinate their seeds using either a solid media such as perlite, vermiculite or coconut fibers or a woven media such as rock-wool. The first germination alternative has the problem of making transplant stress higher, while the second has the problem of being too expensive (for most hobby and commercial growers). With that in mind, I intend to explain on this post how to germinate your seeds using a cheap cube of polyurethane foam which is readily wet by the nutrient solution and generates almost no transplant stress when moving the plants.

The first step to germinate seeds in polyurethane foam is to buy a sheet of the adequate polyurethane. For this purpose, I use a polyurethane foam with a density of 0.015 grams per cubic centimeter. The next step is to cut the polyurethane foam in 1 inch by 1 inch by 1 inch cubes. After this is done, you have to make a cut with a sharp knife at one face of the foam cube (this is where the seed will be inserted).

Once your cube is cut and ready, you have to presoak it in water. Simply squeeze the cube under water and let it absorb all the liquid it can. Once you take it outside, do not squeeze it again since this will make the cube exchange the water it just absorbed for air.

Now simply deposit each seed inside a cube and place the cube in a tray for seed germination someplace where the appropriate conditions for the germination of your seeds are present. You can keep the seeds and the surface of the foam wet by misting water over the cubes everyday. Once the seeds germinate you can place them in your favorite hydroponic setup and the roots will grow out of the foam cube, into any solid media or nutrient solution. (below, an image of my germination setup ready for seed placing).

Salt Concentrations in Hydroponic Tomato Cultivation, More or Less ?

2009-02-19T05:00:00.001-08:00

One of the most produced vegetables in hydroponic growing, both hobby and commercial, is the tomato. Because of this, and the very important place tomatoes have in world economy, many research efforts have been done towards the production of better quality crops. In hydroponics, much of this effort has been devoted towards the investigation of the optimum concentration levels of hydroponic tomato nutrient solutions. In particular, several researchers have studied how salt concentrations are associated with flavor in tomato crops.

Several peer reviewed studies have focused on this problem and many have drawn contradictory conclusions. Some studies suggest that higher EC levels are better for tomatoes while others sustain that it makes no difference in taste or nutrient composition but it decreases fruit size due to the higher osmotic pressure of the nutrient solution.

For example, a recent 2007 study, found out that tomatoes grown with an electrical conductivity of 2.3 and 4.5 dS/m had significantly different nutrient compositions and tastes with the tomatoes grown at 4.5 dS/m being far more tasteful and nutrient rich.

The difference seen amongst the studies is mainly because of the inherent composition of the nutrient solutions. Because different ions have different conductivities, some studies may show different results because of important changes in their nutrient compositions. Hence, even though conductivities are exactly the same, available ions to the plant are completely different. It can be seen that solutions that have higher potassium to nitrogen ratios and higher electrical conductivities prove to improve flavor consistently in hydroponic tomato crops.

Selenium in Hydroponic Growing of Lettuce

2009-02-18T02:00:00.000-08:00

Hydroponic culture has a very good fame of giving optimal conditions for plant growth and nutrition. It is known that hydroponic crops grown with the best possible conditions can attain results far superior than those obtained with any form of soil gardening. However, the research community has just recently became aware that hydroponic growing may not only be used to provide the best conditions for growth but to enhance the plant's nutritional values in ways that were not possible before.

So how do we enhance plants beyond what can be done with traditional hydroponics ? One way is to add certain non essential nutrients to the solution that can make the plants become more nutrient rich. This for example, can be done with the addition of selenium to certain plant cultures, specially lettuce.

Selenium (Se) is a chemical element which is essential to human life. Selenate, the chemical form in which Selenium is absorbed, is a powerful anti oxidant whose daily recommended value is rarely attained with traditional diets. By adding Selenate to the nutrient solution of hydroponic lettuce crops the plant's Selenium content can be enhanced to supply the required daily values of Se.

Recent peer reviewed studies have shown that concentrations from 2 to 6 ppm of Selenate can increase the Selenium content of both lettuce and tomatoes as well as provide an important increase of other antioxidants in tomato crops. This is a clear example of how the inclusion of additional chemicals in the nutrient solution can enhance the nutritional quality of plants and make them go beyond what they would achieve under "optimum" natural conditions.(Below, the chemical structure of the Selenate anion)
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Titanium Dioxide as a Disinfectant in Hydroponic Gardening

2009-02-17T02:05:00.000-08:00

As I have said on previous posts, the problem of disinfection in hydroponic gardening continues to be a main issue in the area of soil less culture. Although there are many chemical solutions such as sodium hydrochloride and hydrogen peroxide, they continue to be non discriminant oxidants with the potential to damage roots and more importantly beneficial symbiotic microorganisms. Therefore, the use of chemical disinfectants takes away the possibility of using applications of beneficial organisms to boost crop yields.

Non chemical ways of disinfecting nutrient solutions do exists but are most of the time extremely expensive and only viable to large commercial growers. Examples of these are UV and ozone sterilization. Both processes are more friendly than chemical disinfectants and are friendly with root beneficial microorganisms, their only drawback is the high cost and difficulty of installation.

Nonetheless there is another potential way of sterilizing nutrient solutions which is both economically feasible for small growers and friendly with beneficial microorganisms that interact directly with plant roots. This new sterilization mechanism uses titanium dioxide as a mean of fighting pathogens inside the hydroponic nutrient solution.

Titanium dioxide is an innocuous, insoluble solid which is vastly used in the food and paint industry. Besides this, antase, a specific crystalline form of this material, has very interesting photocatalytic properties. For example, when irradiated with UV rays (the sun's being enough) antase is able to decompose organic matter into non harmful chemicals. It has been widely studied as a means of replacing hypochloride in water treatment plants and now offers a great way to sterilize nutrient solutions in hydroponic growing.

Degussa P25, an anatase containing nano crystalline commercial form of titanium dioxide, is very cheap and adequate for it's use as a sterilizer in hydroponic growing. Simply, the solution is passed through a shallow open container that has several tiles of cheap glass covered with a small layer of sinthered Degussa P25. This sterilizer can eliminate microorganism spores, bacteria, etc, from the nutrient solution while keeping costs and chemical disinfection down to a minimum. This is something I am going to try in the near future so stay tuned to see my results ! (below, a SEM image of titanium dioxide nano particles)
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Checking the pH of your Hydroponic System, The Easy Way !

2009-02-16T09:32:00.000-08:00

Growers often think that they need to buy pH meters in order to accurately control the pH level of their hydroponic nutrient solution. Actually, there are a couple of ways in which pH can be readily monitored without any digital equipment. One of the cheapest ways in which this can be done is through the use of an acid base indicator.

An acid base indicator is a substance whose protonated and deprotonated molecular forms have different electronic structures with different spectroscopic properties. Therefore, an acid base indicator changes it's color according to the pH value of the solution and this color change can tell us if the pH of our nutrient solution is right or wrong.

Every indicator has it's own characteristic proton affinity which means that it changes at a different pH value. Since the optimal pH in hydroponic growing for most species is between 5.5 and 6.5, we will use an indicator that changes around this value and can tell us if the nutrient solution differs from the ideal setup.

The indicator which best suites our needs is Chlorophenol Red. This substance changes color from yellow (pH 4.8) to red (6.4) (wikipedia is wrong about it changing to violet !), at the pH of our interest, which is 5.5-6.0, the indicator is orange. You can buy an already prepared solution of the indicator ready for testing here. A 100mL solution will allow you to perform thousands of tests at 1/10th of the cost of a regular pH meter.

In order to test the pH, add about two tablespoons of the nutrient solution inside a transparent glass, then add two or three drops of the indicator, mix and watch the results. If the indicator is either red or yellow, you are off the desired value. If the solution turns orange, your nutrient solution's pH is just about right ! (Below, the color change of the indicator as a function of pH, notice that the orange region is precisely around 5.5-6.0 .

Building a Cheap System to Grow Hydroponic Lettuce

2009-02-14T03:46:00.000-08:00

In an earlier post, I talked about a static hydroponic lettuce system that needed no aeration or recirculation and worked by providing an air space between the nutrient solution and the plants. Today I am going to explain how to build this very simple system from cheap materials. These are the things you will need :

- 8 Nails - 2 inches (5cm) long
- 40 Nails - 1 inch (2.5cm) long
- 4 wooden boards - 100 x 10 x 2cm
- Plastic lining (greenhouse polyethylene) - 1.20m x 1.20m
- Knife
- Styrofoam board - 100 x 100 x 2 cm
- Silicon Paste Sealant
- 1/4 gallon white latex paint
- painting brush

The first thing you need to do is nail the boards together forming a 1 x 1m frame. To do this I used 8 large Nails.
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After the boards are nailed together (like it is shown above) paint the outside using white latex paint. This provides protection for the wood from water, light, bacterial and fungal damage. Now line the frame with the plastic, nailing it on the borders using small nails.
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Your system should look like the one shown above. After this part, we need to build the cover of the system that will hold the lettuce plants. Cut 42 2x2 cm holes on your Styrofoam board in a 6 x 7 fashion, keeping a distance of 12 cm between holes. This is shown below.
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Now you need to glue this Styrofoam piece on top of the frame you built before. Do this using silicon paste, taking care to afford a good seal along the whole structure. This will prevent light from reaching the nutrient solution. The holes are fit to accommodate 42 plants (but you may do less holes if you desire to nurture less plants) germinated in polyurethane foam. Later this week I will continue to explain how plants need to be germinated and transplanted in order to use this system and how the nutrient solution is used and replaced. Below, a picture of the finished system (total cost for me, 25 USD).

My pH Balancing System for Hydroponic Growing

2009-02-13T04:34:00.000-08:00

In the past few days, several people have asked me how to use my carbonate/citrate buffering system as a means to control the pH of their nutrient solutions. For this reason, I decided to write a post which explains the simple way in which my buffering system can be prepared and a little more about how it works and what you can expect from it.

A pH buffer's function is to provide reaction "alternatives" for strong acids and bases when they contact the nutrient solution. These acid or basic substances generally react with water and this changes the value of pH. When a buffer is present, they react with the buffering molecules instead of water. This of course, makes pH remain approximately constant. Since the generation of species can be perfectly controlled and predicted by the use of mathematical methods, we can create very good buffering system by "experimenting" with different substances using a computer, as I mentioned in an earlier post.

As a result of my simulations I concluded that a mixture of citric acid/carbonate acts as a good buffer in hydroponics both towards the addition of acids and bases. The actual species involved are citrate and the bicarbonate ion, the bicarbonate ion reacts with acids, providing basic pH buffering, while the citrate reacts with acids providing an acid range buffering effect.

It is very easy to use this system by using your regular pH meter. Prepare your nutrient solution as usual, at the end, add 5g of citric acid for 500 liters of solution (this will acidify the pH of your solution a lot). Now, take back the pH to the value you want (5.8 to 6.2) by adding potassium carbonate. It is important not to use bicarbonate as this will react quickly with citric acid to form carbonic acid and then carbon dioxide (which will leave as a gas !). Also make sure you add both chemicals previously dissolved in water to afford quick chemical equilibrium achievement inside the solution.

By using this method you will have a nutrient solution that is perfectly buffered at your desired pH and that will remain at that pH value for a good amount of time. This of course, depending on the solution's volume and the type and number of plants you grow with it. (below, the distribution of species diagram or the carbonate family)
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One Plant Hydroponic System, Wick Growing

2009-02-12T03:37:00.000-08:00

Most hydroponic systems today are a fairly complicated combination of holding materials, irrigation systems, aeration pumps, etc. For most people wanting to grow a single plant in hydroponics it has become quiet impossible to figure out where to find a cheap system to do so.

One of the cheapest systems available for hydroponic gardening of small plants (ideal for experimentation and school projects) is the hydroponic wick nutrient system. This system uses an absorbent fiber to carry on nutrient solution by capillary action towards the plant which usually rests above it. Wick systems are very easily built and are a very good fit for the growing of small plants.

Medium sized and large sized plants start to have problems with hydroponic wick systems due to the inherent capillary flow limitations that physics impose on the flow of nutrient solution. The absorbent fibers on capillary systems are also often clogged because of nutrient salt buildup (due to water evaporation because of the large surface area of the fibers). Water evaporation increases the concentration of salts along the fiber and starts to precipitate insoluble calcium and other metal phosphates. These are very hard to redissolve and often cause the system to stop working.

However, as I said before, wick systems such as the one built here are very appropriate for experimentation, growing a single hydroponic plant or doing school projects. The system is very easy and cheap to build.(below, a photograph of plants being grown on this system, note that they are very etiolated due to lack of proper lighting)
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Outdoor Hydroponics, Growing Without a Greenhouse

2009-02-11T04:37:00.000-08:00

Most hydroponic gardening techniques demand strict control over the growing media and ambient variables in order to have a crop in optimum conditions. However, most small hobby and commercial hydroponic gardeners do not have the budget necessary to build a greenhouse and need to have their systems exposed to the elements. This is why I decided to write a post about growing hydroponic plants in outdoor conditions, to show growers that hydroponics can be grown outside if adequate precautions are taken.

So what is the problem with the outdoors ? Well, the main problems are temperature changes, rain, haze, snow and excess light. Plants grown outside a greenhouse do not have any protection against direct sun, rain, haze or snow and are therefore most likely to be damaged by the elements. This of course, does not mean that the crops cannot be taken outside.

In countries where there are four seasons (and winter has snow), care needs to be taken not to grow any plants during the winter, because snow will most likely kill all the crops. furthermore, low temperatures are likely to freeze the nutrient solution, something that can be a really bad problem in a hydroponic garden.

Another precaution that needs to be taken is to be specially watchful of the levels of EC in the hydroponics garden. In this special case, nutrients need to added in order to compensate for dilutions caused by rain. Electrical conductivity levels need to be taken before and after a rain storm in order to know the change in EC and return it to normal after. Note that this is a special case, normally nutrients should never be added to a solution which was naturally depleted by the plants. Please read the EC FAQ post for more information about this.

Another important thing is that plants should be protected from excessive evaporation by using hydro-gels. These polymers are applied over the plants root ball and effectively retain moisture for the plant so that possible stress from excessive evaporation becomes minimal. If the sun is too strong, additional measures such as nutrient reservoir cooling (with ice for example) have to be done in order to maintain adequate temperatures around the root zone.

It is clear that hydroponic crops can be grown outside but growers have to take special precautions with this area of hydroponics and commercial growers using this technique should have the losing of one crop a year in their budget (for crops such as lettuces) due to ambient conditions ruining their growth. (below, an image from a special program done by the UN to help poor people use hydroponics as a stable source of income)
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Ion Selective Electrodes in Hydroponic Culture

2009-02-10T05:30:00.000-08:00

Currently, hydroponic growers rely on a combination of electrical conductivity and pH measurements in order to assess the quality and durability of their hydroponic nutrient solutions. However, many are unaware that hydroponic gardening can be much furtherly enhanced by the addition of ion selective electrodes.

In a certain sense, all hydroponic gardeners have used an ion sensitive electrode since the pH meter they use to measure the concentration of H3O(+) ions is actually selective to that ion. Imagine if every time you read pH you had interference from all the other ions present inside the hydroponic solution. Nonetheless, there are currently a large variety of ion selective electrodes available and many of them can be used in hydroponic gardening to accurately control the concentration of several elements.

For example, ion selective electrodes with very good selectivity and little interference exist for the nitrate ion. These type of electrodes can be purchased from many manufacturers but can be easily found here. For just 229 USD, the grower is able to accurately control the amount of nitrate ions present inside the hydroponic solution independently from other nutrients.

By measuring the potential difference given by the electrode when the solution is prepared, the grower is able to easily detect and graph changes within a certain growing period. Best of all, since the ion selective electrode gives a real measure of ion concentrations, the grower is able to resupply spent nitrogen without unbalancing the hydroponic growing solution.

Ion selective electrodes exist for a variety of ions including nitrate, ammonia, phosphate, potassium, iron and copper. This technology will prove to be the future of hydroponics as it will guarantee the grower the ability to accurately control and resupply the exact amount of nutrients needed by his or her growing plants. These electrodes can also be easily wired to computer software in order to monitor nutrient use 24/7 (below a display of several ion selective electrodes)
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Growing Citrus Trees in a Hydroponic Garden

2009-02-09T03:55:00.000-08:00

While hydroponic gardening is most often done with plants like tomatoes, lettuce and bell pepper, it is well known that the hydroponic growing technique can be applied to a large variety of plants with different degrees of success. One type of plant that is an all time grower favorite is the citrus tree. Plants such as orange, lemon and mandarin (called citric because of their high citric acid content) can be grown effectively in a hydroponic garden.

Before you start your quest for a hydroponic citrus tree, beware that this type of plant demands somewhat warm weather and high amounts of light. These plants are not very good at indoor growing unless some LED growing lamps are used to complement lightning (although high pressure sodium and halide lamps can also be used).

Once you decide to grow a citrus tree the first step is to either find a suitable candidate from a nursery or grow your own from seed. If you want to grow from seed, beware that it will take the plant 3 to 5 years in order to start bearing fruit. If this is unacceptable, find a plant at a local nursery that has the age you require. If you are growing from seeds, soak the seeds inside a napkin for 2 days and then remove the external seed coating. This guarantees effective germination once the seed is planted.

For the best results, I recommend using a 5 gallon container filled with rice husk, perlite or vermiculite fitted with adequate tubing at the bottom for nutrient solution evacuation. I recommend installing a drip irrigation system with at least 3 drip emitters per citrus tree you planted.

As for the nutrient solution, I recommend using a Hoagland solution, first at half strength and then at full strength as the plant starts to grow. Your hydroponic citrus tree will not probably grow as big as an actual citrus tree but will bear fruit of normal size and sometimes even in the same quantities. Since your tree is in a hydroponics system, it will (if the solution is taken care of) never have to face any iron or manganese defficiencies common to soil grown citrus trees. Sometime in the next month I will publish a detailed how to on the construction of the hydroponic system itself.
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Beneficial Fungi in Hydroponic Gardening

2009-02-08T03:53:00.000-08:00

In common hydroponic culture, the growing media and the hydroponic nutrient solution are kept sterile in order to guarantee the absence of malicious plant pathogens. This however, changes the root environment dramatically and places plant roots in a media which is totally inert and different from the media in which they evolved, soil.

However, hydroponic gardening offers an important advantage in that adequate beneficial microorganisms can be cultured with our hydroponic plants, making the root environment change towards a much more soil-like beneficial media whith stimulated nutrient absorption, prevents pathogens and increases growth.

Amongst all the microorganisms that can be introduced into hydroponic media, none are as beneficial as the fungi commonly known as mycorrhiza. This term refers to fungi that create important symbiotic bonds with the plant's roots, activating the plant's internal defense mechanisms and boosting it's nutrient uptake capabilities by using the fungus's hyphae as nutrient uptake vehicles with a much higher surface are than common plant roots.

In practice, I have introduced Trichoderma species of fungi into my hydroponic solution every crop for the past 2 years with very good results. Trichoderma visibly stimulate the plant, making it vigorous and more productive than a traditional hydroponic plant. The fungi also increase the plant's ability to assimilate phosphorous, something which is a problem where I live due to low ambient temperatures (which hinder P uptake). In order to use Trichoderma efficently in your hydroponic solution you should lower the amount of phosphorous under 40 ppm because higher amounts of this element inhibit the fungi's development.

With this in mind I hope that all of you who have considered biological help in your hydroponic garden will start using these incredible microorganisms which are very good at helping your plants develop and maintain an adequate level of productivity. (Below a picture that shows the difference between plants with and without beneficial Trichoderma spp fungi)
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The NFT Hydroponic Growing System

2009-02-07T04:35:00.000-08:00

In the last 50 years, many hydroponic systems have been developed in order to make crop cultivation easier, cheaper, faster and denser. Amongst the systems that have been developed, one of the hydroponic systems which has caught the most attention and is used more frequently is the so called NFT (Nutrient Film Technique) system.

The system's operation principles are quiet simple. A PVC (or or other polymer) rain gutter is placed on an aluminum frame with a certain inclination, plants are placed in small containers introduced inside the gutter and a nutrient solution is sprayed at the most elevated side of the gutter. The spraying forms a thin film on the gutter's bottom and flows towards the other end due to the slope.

The fact that the NFT system allows most of the plant's root system to remain outside the nutrient solution is the main reason for it's success. Throughout a lot of research, it has been found that plants just need to be "barely" in contact with the nutrient solution. Plant's seem to greatly benefit from their roots abosrbing oxygen from open air and taking just the little amount of necessary nutrients they need by a small contact with nutrient solutions.

The NFT system is great for crop cultivation and is one of the most efficient systems for the growing of crops such as basil, lettuce, spinach and cabbage. However it does have some disadvantages such as gutter length limitations due to nutrient and temperature changes (usually gutters are never more than 15 feet long), of course they also have the strong disadvantage of much higher costs (fue to the gutters being expensive) and lower planting densities (due to the spaces needed between gutters to allow personel). Nonetheless, many companies growing NFT systems have been able to make "foldable" gutters which allow automatic recollection of lettuce, transplanting and sterilization.

In conclusion, one could say that the NFT system is one of the best hydroponc growing systems that have been developed due to the fact that it allows greater oxygen and nutrient absortion. In fact, the hydroponic nutrient film technique is one of the most used systems for lettuce cultivation.
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Disinfecting your Hydroponic Solution with Hypochlorite

2009-02-06T03:56:00.001-08:00

As I talked about in a previous post, the disinfection problem in hydroponics is very important as many pathogenic microorganisms as well as algae develop through the course of any hydroponic gardening attempt. Hydrogen peroxide, as I said earlier, is a very good disinfectant with incredible properties but most of the time it is not used because of it's high cost.

Amongst one of the most common disinfectants available we find sodium hypochlorite. This chemical substance with formula NaClO is a good disinfectant because it oxidizes organic matter producing Cl2 which then further oxidizes organic matter tu produce Cl(-). As you can see, the several steps available for oxidation as well as this compound's innate reactivity make it one of the best and cheapest disinfectants available today. This is the reason why sodium hypochlorite solutions have been used for a long time and now have commercial names, such as Clorox.

In hydroponics, sodium hypochlorite solutions are commonly used to sterilize a hydroponic system prior to use or in between different crops. However, this does not achieve the purpose of maintaining the nutrient solution sterile throughout the whole gardening cycle.

In order to achieve this in a very simple way (for the home hyroponic and commercial gardeners) several peer reviewed papers have studied the effect of hypochlorite ions on different plants and at different levels of concentration. In general, it has been found that concentrations of hypochlorite of 5.5 ppm offer good protection agains microorganisms without affecting the crop qualities.

If you do not have any industrial grade hypochlorite you can still achieve this concentration by applying 0.1mL of Clorox (check that it is less than 6% hypochlorite, usually 5.25%) per liter of nutrient solution. This can be easily measured and applied for small systems with the aid of a 1mL syringe as the ones diabetes patiens use for insulin (these syringes can be easily purchased at any pharmacy). Remember to try this with a small batch of plants before applying it over your whole garden to ensure compatibility with your particular nutrient solution.
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Preparing Hydroponics Nutrient Solutions, From Concentrations to Weights

2009-02-05T15:02:00.000-08:00

In a previous post, I explained how concentrations are given in hydroponic gardening and what they actually mean. For example, I exemplified that 200 ppm of N equals a solution which contains 200 mg per liter of nitrogen although the form in which nitrogen is present is not described by the concentration data. In this post, I intend to explain how nutrient concentrations can be translated adequately to a mass weight of a certain salt that will be the actual source of the nutrient.

Let us start by supposing that you have a certain solution recipe given in concentration data, for example, the solution demands 200 ppm N and 700 ppm K (this is just an example as 700 ppm of K is too high for any hydroponic nutrient solution). This means that the solution requires 200 mg per liter of nitrogen and 700 mg per liter of potassium. Our mission now is to translate this concentration information into the actual amount of a given salt that needs to be weight and dissolved.

The first thing we need to do is find a suitable salt or salts that can give us the nutrients we want in the appropiate forms. In this case, we will use potassium nitrate (KNO3) as a source of both nitrogen and potassium. This salt gives the plant nitrogen as NO3(-) ions and potassium as K(+) ions.

Our next step is to figure out how much solution we want to prepare. In this case, let's suppose we want to prepare 100L (around 32 gal) of nutrient solution.

Following this, we must calculate how much much K(+) and how much NO3(-) need to be added in order to achieve the concentrations we desire. Since K(+) contains a single K atom, we need 700 mg/L of K(+) in order to achieve 700 ppm of K, for the nitrate ion (NO3(-)), since it contains more atoms, we need to know how much of the nitrate ion is actually nitrogen. In order to do this we calculate what fraction of nitrogen resides in nitrate by relating their molar mases (you can google nitrate molar mass and nitrogen molar mass to get this values or calculate them using your periodic table) . The calculation would be 14/62 which equals 0.22. This means that 22% of each nitrate ion is nitrogen. If 22% of each nitrate ion is nitrogen then we need 200ppm x(100/22) of nitrate in order to get the concentration of nitrogen we want. The result is that we need 909 mg of nitrate per liter in order to achieve our required concentration of 200 ppm.

Since our salt is KNO3 and not K or NO3 by themselves we need to decide which nutrient we want to fit in an exact manner. For this example I will take NO3(-). Since we want to weight 909mg per liter of NO3(-) we see how much KNO3needs to be weight in order to achieve this amount for 100 liters. For this we use the relationship between the molar mases of nitrate and the salt, potassium nitrate. The equation is 62/101, which equals 0.61, meaning 61% of potassium nitrate is nitrate. Since we want to know how much is 100% knowing that 61% is 909mg per liter we calculate 909ppm x 100/61, which equals 1490mg per liter which needs to be multiplied by 100 in order to find the amount needed for 100 liters of solution. The final result is that 149 g of potassium nitrate are needed in order to achieve a concentration of 200 ppm of N in 100 liters of solution.

Now what happened to the potassium ? Since we added potassium nitrate, we also added potassium with the salt. We now need to calculate the concentration of potassium which we get when we arrive at a concentration of 909 ppm for ntirate. Since we know nitrate is 61%, then potassium must be 39% of the concentration so 1490 ppm x 0.39 equals 581 ppm.

As you can see, we matched our nitrogen requirement perfectly but ofset our potassium requirement by an important amount. This problem is due to the fact that each salt gives two nutrients to a soltuion. Meaning that a good salt combination needs to be used in order for our errors to be reduced when preparing the hydroponic nutrient solutions. This problem can be solved by using the hydroponic nutrient solution calculator I described in an earlier post, however, it is important to know how the calculator works in order to understand its possible errors.

As you can see, preparing nutrient solutions and turning concentrations into weights can be a little bit daunting at first but with practice and the aid of calculator tools, the preparation of custom hydroponic solutions becomes very easy and paves the way towards major improvements for any commercial or hobbyst hydroponic gardener.

Describing Concentration in Hydroponics

2009-02-05T03:55:00.000-08:00

Most amateur growers, both hobby and commercial, who do not have a chemical knowledge background are most of the time stunned by the amount of chemistry involved in hydroponic cultivation. One of the things that proves to be the most difficult for this new comers is the understanding and description of nutrient concentrations.

Concentration, to start, is just a way of expressing the amount of something inside something else. In hydroponics, we are interested in expressing the amount of nutrients per amount of nutrient solution. To do this, we use several tools available in chemistry.

In general, concentrations in hydroponics are either expressed as moles of nutrient per liter of solution or as milligrams of nutrient per liter of solutions. The first unit is called molarity while the second unit is generally referred to as ppm (parts per million). This means that a solution containing 12 ppm of Nitrogen contains 12mg of nitrogen per liter of solution and a solution containing nitrogen in a 0.001M concentrations contains 0.001 moles of nitrogen per liter of solution. The first form of concentration (ppm) is often used in hydroponics while the second (M) is used in hydroponics only in research papers and such.

In practice, the use of concentrations in ppm makes preparation a little bit easier as the leap from concentration to mass becomes easier if the unit of measurement inside the unit belongs to mass. Since the ppm unit can be translated as (mg/L) going to the mass of salt required is easier than with molarity (although not by much).

Another advantage that we come across when using ppm as a main unit of concentration measurement in hydroponics is that the numbers are likable. We, humans, tend to like numbers between 0 and 1000, so concentrations of 120 ppm, 250 ppm and such, seem much easier to grasp than their equivalents in molarity which would be 0.0012 M, 0.00023 M or the like.

In an article to be written soon, I intend to describe how to do the leap from this concentration measurements onto the mass of salt that is needed to weight in order to achieve the desired concentration inside a hydroponic solution. So stay tuned to know a little bit more about the science of hydroponic nutrient solution making !
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Nitrogen Fertilization in Hydroponics

2009-02-04T06:58:00.000-08:00

It is a common mistake in hydroponic gardening to assume that the chemical forms of nitrogen that can be used in hydroponics are the same that can be used in regular soil gardening. Don't get me wrong, plants in soil and plants in hydroponic media use the exact same chemical forms of nitrogen as nutrients, what changes dramatically from hydroponics to soil gardening is the environment in which the plant is.

Let us talk about the available forms of nitrogen first. Plants absorb nitrogen either as NO3(-) (nitrate) or NH4(+)(ammonium) ions. Both of these ions supply nitrogen to the plant but they have dramatic differences inside the plant's metabolic pathways. Nitrate is absorbed by the plant slowly and provides the materials needed for the synthesis of amino acids and other structures while ammonia is absorbed rapidly and causes immediate plant toxicity if present in highly enough concentrations.

This is the main difference between soil and hydroponic gardening. In hydroponics, most of the nitrogen must be supplied as NO3(-) because the hydroponic media allows ammonium ions to become toxic exceedingly fast. For example, hydroponic plants can withstand concentrations of nitrogen (as nitrate) up to about 250 ppm while concentrations of nitrogen as ammonium are only withstood up until about 30 ppm. This is the reason why urea cannot be used as a nutrient salt in hydroponic gardening to supply all the nitrogen needed by the plants.

So if plants in soil and hydroponic media assimilate the same nutrients, why can plants in soil be fed nitrogen as ammonium but hydroponic plants cannot ? The answer is quiet simple. Bacteria present within the soil are able to efficiently convert ammonium ions into nitrate ions, effectively reducing the amount of ammonium the plant "sees". In fact, plants in soil also absorb nitrate, the only difference is that there are bacteria that can convert ammonium to nitrate, reason why nitrogen can be supplied as ammonium to plants present in soil.

So next time you are searching for a nitrogen nutrient for your hydroponic plants, remember to search for nitrate salts as more than 90% of your total nitrogen source. The most important salts for providing nitrogen as nitrate in hydroponic gardening are potassium nitrate and calcium nitrate. This is important to remember, as using ammonium salts to provide your plant's nitrogen will ultimately kill them in hydroponic media ! (below, an image showing the effects of ammonium fertilizer in hydroponic plants)
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Rooting Cuttings Naturally

2009-02-04T06:43:00.001-08:00

When gardening, it is sometimes most convenient not to start a plant from seed but to start it from a cutting from another plant. Most of the time, the science of starting cuttings involves the use of root growth hormones and other chemicals which can prove hard to get in some regions of the world and sometimes are not desirable because of their conflicts with some organic food regulations.

Luckily, there are ways to root and get cuttings up to a good start without the use of any root hormones. In order for us to do this, we should first understand the problem and how to solve it.

When a part of a plant is cut, and this part has no root system, the ability of the cutting to get nutrients from it's surroundings becomes minimal. The idea is to maintain the plant's food requirements as low as possible until it develops a healthy root system that can take up nutrients and grow a healthy new plant.

The first step is to place the cutting inside some growing media (remember to cover the cut wound with candle wax in order to prevent possible fungal infections) (either potting soil in soil gardening or perlite, rice husk/ sand in hydroponic gardening) and to place it somewhere where light is scarce. When diminishing the amount of light that reaches the cutting, we slow down photosynthetic processes and therefore the nutrient needs of the plant. The media should be watered daily so that the new root system can be developed.

In order to supply nutrients for the plant, a suitable foliar spray should be applied. A 1/10 strength Hoagland's solution can be used effectively or a suitable organic foliar spray can be used if the desire to achieve organic food certifications is present. Plants are able to feed throw their leaves in some way so the application of nutrients on the leaves or "foliar feeding" is a good tecnique when starting cuttings whose root systems have not developed.

After 3 or 4 days of this process, the plant should be ready for it's reintroduction into normal growing conditions. If you are a hydroponic gardener, start applying a one third strength hydroponic solution on the plant's growing media. In any case, the plant should be brought into light in increasing intervals, first day one hour, second day 2 hours, third day 4 hours, fourth day 8 hours and fifth day left outside.

This whole process should provide an adequate environment and growth for the new cutting's root system with the final gradual adaptation providing enough time for the leaves to readjust to normal lighting conditions. I hope this guide proves useful and all of you enjoy new cutting in your organic or hydroponic gardens.
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An Organic, Natural Insecticide for your Garden

2009-02-04T06:28:00.000-08:00

Few people have been able to experience the joy of gardening without encountering the nasty problem of insects. Every year, many gardens suffer from the amazing attacks of these small creatures that turn beautiful plant spaces into infested focuses of insect populations.

Up until now, most chemical solutions have acted on insects quiet effectively. In fact, some insecticides are good at removing more than 99.99% of insect populations with a few applications. Chemical insecticides are most of the time harmful for humans but sometimes they can even be safe for us. The main problem with synthetic insecticides is that they affect beneficial insect populations much more dramatically than they do harmful insect populations. The main problem with this is that is effectively diminishes the amount of insects that can predate bad insects and pollinate plants.

Organic (in the sense of natural) insecticides are sometimes good but they are never as effective as available synthetic solutions. In the few studies done about this issue, (mainly dealing with cabbage) all of them have found synthetic solutions much better at controlling insect pests. However, garlic based insecticides have proven effective at controlling insects if not completely removing them from the garden (they also prove almost non fatal to beneficial insect populations).

In order to control your insect populations easily, you can manufacture an insecticide with garlic, vegetable oil and water. Cut 3 cloves of garlic into small pieces and place them in a jar with 200 mL (about a cup) of vegetable oil for two nights (this ensures that the organic non polar molecules present inside garlic are extracted efficiently). Next, mix this with 2/3 of a gallon of water . Agitate strongly before each use. Then your insecticide is ready to be spread on your garden.

Hopefully, if spread adequately over every inch of the plant (including the underside of leaves), the insecticide should prove efficient against most types of bad insects. It also proves effective in being resistant to rain so your plants should remain protected for a prolonged amount of time. Bear in mind that soap or detergents should not be added to improve surface tension properties because this increases the capacity of rain to remove the insecticide effectively.
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FAQ - controlling, adjusting and knowing pH in Hydroponic Gardening

2009-02-03T15:46:00.000-08:00

Even though there has been great effort by many people to show hydroponic growing as something that can be done by anyone with little knowledge, it has come to my attention that many novice and commercial gardeners fail because of their inability to properly interpret the chemical phenomena around them. One of the variables that is primordial in hydroponic culture and that is grossly oversimplified in most literature about hydroponic gardening is the treatment of pH. For this reason, I decided to create this pH FAQ post in order to answer (in a basic but scientific way) the questions most people have (or should have anyway) about the science of hydroponics.

What is pH anyway ?

This is the most basic and important question. In layman terms, pH is a measure that tells you if a solution is acid or basic, with values of pH over 7 being basic, and values below 7 being acid. Going a little bit deeper into detail, pH is just the result of applying the operator "p" over H (which symbolizes the concentration of H3O(+) ions within a solution). The operator "p" is just getting the negative decimal logarithm of a number. Since H3O(+) concentrations appear usually in really small magnitudes, like 0,00000001 M, using the logarithm let's us express this in more humanly understandable numbers, like 9.

Why is 7 the neutral pH ?

Seven is the neutral pH value because the concentration of H3O(+) ions in solution is determined by the self dissociation constant of water which is 1x10e-14 and equals the product of H3O(+) and OH(-) concentrations. If H3O(+) concentrations are equal to OH(-) concentrations you have that H3O(+) concentration should equal 1x10e-7 which after applying "p" turns into 7.

Why is pH so important in hydroponics ?

This variable is very important in hydroponic gardening because it determines the form in which nutrients are present inside the solution. In pH values which are too acid or too basic, nutrients assume forms which are different from the ones which plants can assimilate. Therefore, an adequate pH value needs to be maintained in order to ensure that all nutrients are present as the right species.

How do I measure pH correctly ?

First of all, pH meters need to be calibrated prior to each measurement. In order to calibrate any pH instrument, at least two different buffer solutions must be used, one with pH 7.0 and the other with any other known pH value. The measurement should be taken with enough time for the reading on the instrument to stabilize.

How can I correct pH changes ?

Bases or acids can be added to hydroponic solutions in order to increase or decrease the pH value of a solution. Bases and acids should be added as solutions and the amount added must be recorded in order to know how nutrients are changed. For example, if a potassium hydroxide solution is added to increase the pH of a solution, the amount of solution added needs to be recorded in order to know how much potassium was added to the solution (since this is a nutrient). Common acids to lower nutrient solution pH values are nitric acid, phosphoric acid and citric acid. I would recommend the use of citric acid to reduce pH and potassium carbonate to increase pH.

What is the ideal pH value ?

It depends on the specific plant you are cultivating. Most crops grow very well with pH values between 5.5 and 6.0, although there are some plants which require more basic or slightly more acid pH values.

How can I stop pH from changing ?

Please refer to the article I wrote about controlling the pH of your nutrient solution with buffers in order to effectively prevent pH variations inside your hydroponic nutrient solution.
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A Natural, Organic Fungicide you can make !

2009-02-03T15:03:00.000-08:00

Amongst all the problems faced by hydroponic and soil gardeners, fungus problems remain one of the most challenging. Fungal diseases tend to start rapidly and quickly wipe out entire sections of plants, leaving the grower wondering what happened or if anything could have been done to prevent it.

Sadly, most commercially available fungicides are very toxic to humans and beneficial insects, a reason why their application is detrimental to both the gardeners health and the environment itself. For this reason, many people have started to develop natural and more environmentally friendly solutions towards the problem of fungicide disease prevention.

Most gardener websites from people with limited knowledge about both fungicidal chemistry and biology offer simple solutions that may work with decent results for fungicide prevention and in some rare cases for fungicide disease curing. These remedies also carry some problems of their own, for example, the use of milk containing solutions over plants is proved to encourage the growth of molds and sometimes even stimulate the gathering of ant or similar insect populations. Using alkaline solutions containing bicarbonate or carbonate ions may prove beneficial for prevention but it's effects are readily lost due to rain (which inevitably washes away bicarbonate ions).

In the light of this situation, I have decided to publish the recipe for a fungicide I have been using for sometime, based on US patent No. 6767562 (you can google the patent if you would like to further improve your knowledge on the matter). This mix was designed with both the chemistry and biology of fungus diseases in mind, taking into account that most fungus are sensitive to tannic acid and other chemicals naturally present within certain plant species.

This organic, natural fungicide is quiet simple to make. First, add two thirds of a cup of sage leaves to 1/2 gallon of water and boil it down to 1/3 gallon of water. After this has been done, add 2/3 gallon of red wine (the patent says "fermented grape solution" to make it a little bit harder to guess !") and that's it ! The solution has been proven to prevent and even cure fungus diseases in a variety of crops (as stated in the patent). Now, this information is merely educational and freely available within the patent, if you do not commercialize it you are free from patent infringement. I hope you use and enjoy this excellent organic, natural fungicide that will keep your garden free of those nasty, crop ruining fungus pests !
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What are Hydroponic nutrients ? The nature of nutrient salts

2009-02-03T14:41:00.000-08:00

When researchers first started to study how plants grow and what plants exactly need to develop, they found out that plant needs are very different from our own. We, as humans, need minerals, vitamins, carbohydrates, proteins and fats amongst other substances. However, plants seemed to require a small assortment of inorganic substances from which they synthesized a very large variety of organic materials.

Many hydroponic growers are confused by the fact that nutrient needs and nutrient solution compositions are provided in the form of elemental concentration. That is, hydroponic solutions are often described in the form "N 200 ppm", "K 100 ppm", etc. Compositions are expressed as the amount of milligrams present of a given element per liter of solution. Nonetheless, this does not mean that the element is present as a pure substance.

For example, the fact that a hydroponic solution contains 100 ppm of Nitrogen, does not mean that the solution contains nitrogen as elemental nitrogen, that is, N2 gas. This in fact, does not express the form in which nitrogen is present, it may be present either in the form of NO3(-), NH4(+) or other molecules. This has caused some confusion since some people are unaware that hydroponic nutrients are mainly inorganic salts that, when dissolved in water, form ionic substances which are the actual nutrient assimilated by the plant.

It is important then to have a clear mental perspective about the way in which things are expressed and the way in which they really are. For example, you can have a hydroponic solution with 100 ppm of P. That is, a hundred milligrams of phosphorous present per liter of solution but in no way does this express the way in which phosphorous is present within the solution. Phosphorous may actually be located as a large assortment of ions, either H2PO4(-), HPO4(2-) or PO4(3-).

The reason why nutrient solution concentrations are often expressed as mere element concentrations instead of actual available form concentrations is because it is much simpler to think about the sum of all the available forms of a nutrient than each nutrient form by itself. In the light of the previous example, it is much easier to say 100 ppm of P than to state a specific concentration of each ion, given that (in this case) all ions are indistinguishable for the plant.

The really important thing about this is that the grower should have a clear understanding of the nature of hydroponic nutrients. Nutrients are really ions, which are formed by the dissolution of salts in water. So when you go out to buy nutrients for your hydroponic solution you should look out for inorganic salts of the desired elements ! (below, an image that graphically shows ion dissolution)
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Keeping the pH of your hydroponic nutrient solution stable

2009-02-02T18:00:00.000-08:00

A nightmare for many growers inside the hydroponic industry is the fact that pH adjustments need to be made every now and then to nutrient solutions. In fact, people often adjust the pH of their nutrient solutions several times a week in an effort to keep the values close to those considered ideal. However, most growers are unaware of the basic facts surrounding pH changes and how they can be avoided (please refer to the pH FAQ for more information).

The concentration of H3O(+) ions, which are the ions that determinate pH, changes according to other ions present inside the hydroponic solutions. Since plants take ions (which are charged species), outside of the solution, they cause a charge imbalance which is compensated by the generation of either H3O(+) (if the plant absorbs an ion with positive charge) or an OH(-) (if the plant absorbs an ion with negative charge).

One of the ways in which this pH change can be effectively controlled is by the addition of a specie which balances out this charge and offers reactivity against either OH(-) or H3O(+) species. Such addition of species to a solution in order to offer a chemical equilibrium protection against pH changes is called "buffering". In hydroponics, solutions are most often "buffered" using ammonia, however, we can carry out simulations to see how this two ions act against "acid" or "base" additions and see how the entire hydroponic system reacts to this.

The simulations are carried out using the Maxima software and all the equation systems are generated according to equilibrium equations, mass balance equations and charge balance equations (this is called systematic study of the chemical equilibrium). Concentrations for all the buffering agents were treated as 0.1 mM.

Long story short, the graph below shows the results for my simulations of "acid" or "base" additions using three different buffer agents. The blue line shows the change when citric acid/citrate is used as a buffering agent, the orange line shows when ammonia is used as a buffering agent and the yellow line shows when carbonate/citric acid is used as a buffering agent.
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As it can be seen, citrate provides very good buffering capacity towards acid pH values while it's buffering potential towards basic pH values becomes lesser. Ammonia provides almost no buffering potential towards acid pH values while it provides almost the same buffering effect towards basic pH values than citric acid. Note that basic pH buffering seems the same for both buffers because here the effect of the phosphate ions inside the solution becomes more prominent.
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However, when carbonate/citrtic acid is used as a buffering agent, it suddenly turns the solution's buffering power towards both acid and basic pH values, extremely high. That said, it should be expected for a solution with this buffering mix to last several times more than a regular solution without needing any pH adjustments. In practice, the preparation of this solution has given me at least three weeks of plant intake without any need for pH adjustment.

Hydroponic Nutrients, Are they Unnatural ?

2009-02-02T14:25:00.000-08:00

In today's world, things seem to have started to shift towards a more "natural" look at things. People are starting to reject synthetic and "artificial" things in favor of the more "natural" and "earthy". Well, as a scientist, I have to say that most people have some very bad misconceptions about these definitions and their "evilness" or "goodness". Let us start from the beginning.

What is Natural ?

This is usually defined as something that comes from nature without any fundamental modification caused by humans. Therefore, you could say that blood is natural, algae oil is natural, bones are natural, etc.

What is Unnatural ?

Something unnatural can be defined as not coming or not belonging in nature. You could then say that a bee swimming is unnatural or that a plant growing inside a PVC pipe is unnatural.

What is synthetic ?

Something synthetic can be defined as chemically manufactured by humans from chemically different materials. For example, plastics are synthetic, pure sodium is synthetic, carbon nano tubes are synthetic, etc. Now see that this definition is not exclusive, something can be synthetic but present in nature, like synthetic hormones, synthetic vitamins, etc.

Now which is bad and which is good ?

This is where most people have it wrong. Natural things are good ? Well, that depends, which natural thing. You eat and orange and it's good, you swallow a scorpion and its bad. Both things are natural. Nature produces things that are toxic and lethal, but nature also produces things that are good for you. You cannot judge something to be good just because it belong inside a group, every category has both good and bad things.

Are unnatural things bad ? That depends. You smell a neurotoxin, you are dead, you use a sulfonamide antibiotic when you have an infection and your cured. It all depends on the specific thing your talking about and the specific use your giving it. There is no sense in judging something as being good or bad for the sake of it.

Now, are hydroponic nutrients unnatural ?

No ! Hydroponic nutrients have the exact same chemical form nutrients have in soil. Plants cannot absorb these nutrients if they don't have these specific forms so hydroponic nutrients are indeed natural. They are the exact same molecules that are found in soil. Hydroponic gardening is just a form of manipulation in which plants are given an amount of these nutrients that fits their needs optimally. It differs from their natural conditions in that hydroponic growth conditions are better. The plant gets all it's nutrients in the same form it gets them from the soil without needing to break up organic matter to get them or fighting pathological microorganisms. Indeed, hydroponic gardening has both positive and negative qualities, just like everything else !

Hydroponic Gardening for Small Spaces

2009-02-02T14:02:00.000-08:00

People everywhere enjoy the pleasure of growing plants. Most people use their backyards for this purpose, growing ornamental as well as plants used for eating. However, many people around the world don't have a backyard because of space limitations, something which is becoming more common everyday with the growth of world population.

For people who want to grow beautiful flowers, healthy vegetables, herbs and spices in reduced spaces, hydroponic gardening becomes an evermore interesting option.

Hydroponic gardening, which does not use any soil, is ideal for growing many plants. This type of culture has the advantage of not needing any soil and of letting the grower choose the precise composition of the nutrients received by the garden. When this is coupled with a tight space, hydroponic gardening opens up the possibility to grow plants in much higher densities and in much better quality and uniformity than soil based plants.

With living spaces being more populated everyday and commercial soil based vegetables becoming more polluted and damaged, it is evident that the use of currently unused city spaces (such as rooftops) will become very important for the food provisions of the future.

Small hydroponic systems for people with drastic space limitations can be easy to install. From the inside of a closet to a small patio or a window edge, soiless gardening offers the solution to the problem. This systems known as hydroponic grow closets are becoming more and more popular everyday (I will publish a tutorial for building a hydroponic closet soon).

The Hoaglands Solution for Hydroponic Cultivation

2009-02-02T10:48:00.000-08:00

This hydroponic nutrient solution was developed by Hoagland and Snyder in 1933 and it's one of the most popular solution compositions for growing plants (in the scientific world at least !). The Hoagland solution provides every nutrient necessary for plant growth being appropriate for the growth of a large variety of plant species. The solution described by Hoagland in 1933 has been modified several times (mainly to add iron chelates and the like, but you can use the salts you normally use for preparing your solutions as long as you append to the concentrations given for each element) but the original concentrations for each element are shown below.

N 210 ppm
K 235 ppm
Ca 200 ppm
P 31 ppm
S 64 ppm
Mg 48 ppm
B 0.5 ppm
Fe 1 to 5 ppm
Mn 0.5 ppm
Zn 0.05 ppm
Cu 0.02 ppm
Mo 0.01 ppm

As you may notice, the Hoaglands solution has a lot of N and K so it is very well suited for the development of large plants like Tomato and Bell Pepper. However, the solution is very good for the growth of plants with lower nutrient demands such as lettuce and aquatic plants with the further dilution of the preparation to 1/4 or 1/5.

Also remember that the amount of iron you use should be in proportion with the amount of phosphate placed inside the solution, when used at higher strength, there exists the possibility of iron precipitation if non adequate chelates are used. If possible, try using DPTA instead of EDTA (which is not so good a chelating agent for hydroponics).

Indoor Hydroponic gardening, the cheap way !

2009-02-02T10:32:00.000-08:00

Hydroponic gardening is a great way in which plants can be grown and cultivated with yields far superior to those of traditional soil based culture. However, the last frontier of hydroponics remains being indoor growing. Light, which we take for granted because of the sun, is a crucial factor for plant growth and becomes dramatically diminished or non existent inside our house's or building's interiors.

The solution, of course, is using artificial lighting to grow our crops. Unfortunately, the amount of light needed by plants (which is measured in Lumens) is quiet high. In order to fulfill a plant's light needs, high power consuming artificial lights must be used. In fact, most indoor growers use halide lamps which are in the range of 1000 to 2000 watts of power.

The amount of energy consumed by these growing lights is so huge because most of the energy provided to the lights is wasted as heat and little of this energy becomes usable to the plant as light. Other problems also arise because of the excess heat eliminated by this high-powered illumination devices.

The solution for this problem is actually very simple. The use of LEDs (light emitting diodes) for hydroponic growth has become popular because of their low energy consumption (almost 20 times less than regular growing lights). They are simple to install and provide all the necessary wavelengths your plants need for adequate growth. For instance, two tomato plants can be grown with as little as 50 W of growing LEDs while this same tomatoes would consume in excess of 1200 W with traditional lighting. If you are wondering where these lights can be purchased, just search ebay for "growing LED's" and a bunch of sellers that offer these products will come up.
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Hydroponic Floating System for Lettuce Production

2009-02-02T10:21:00.000-08:00

Lettuce is one of the most common vegetables produced in hydroponics. It is amongst the first 3 vegetables produced in hydroponic crops around the world with tomato and bell peppers. Most lettuce production systems are designed around two ideas, either the NFT (nutrient flow technique) system or the floating raft system. The later system is of particular interest because it is highly economical and can produce bast volumes of hydroponic lettuce.

One of the main problems with raft systems is that the fact that the nutrient solution is constantly stagnant demands the use of pumps to circulate water and generate significant aeration. Without this precious oxygen reaching the plant's roots, floating raft systems experience high loses of yields in the form of dry weight, nutrients, etc.

Nonetheless, raft systems can be improved dramatically in order to avoid the recirculation of solution and aeration of the roots by mechanical means. This is done in an exceedingly simple way, by placing the raft not directly above the hydroponic solution but a few centimeters above from the solution itself.

The results are incredible. Without any mechanical aeration or movement, this hydroponic system achieves dry weights superior to any floating raft system published in peer reviewed literature. This research was done by horticulturist B. A. Kratky and was published in the year 2005.

So if you are searching for a cheap hydroponic system which can offer you lettuce in high yields with no power usage, this is precisely the way to go. I will publish a post soon showing how this can be done and how you too can enjoy this great system for lettuce cultivation.
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Hydroponic Nutrient Solution Toxicity

2009-02-01T13:27:00.001-08:00

It has become a common practice for many hydroponic enthusiasts, hobbyists and even commercial growers to dispose of the nutrient solutions they have that "are not adequate anymore" by throwing them down the drain. Most of them are not aware than hydroponic solutions are environmentally contaminating.

Hydroponic solutions contain all the basic nutrients necessary for the development of photosynthetic organism. This of course, means that hydroponic solutions are the ideal source of nutrients for algae growth. When they are disposed of down the drain, the solutions cause algae blooms which are terrible for the environment because when algae populations dye massively, they deprive water of oxygen and cause the death of aquatic organism.

The solution ? It is actually very simple. Have a hydroponic growing container in which plants that you "don't care for" are grown. For example, have a hydroponic growing container in which grass, weeds or other type of "low nutrient requirement" plants are grown. This way, when your hydroponic crop has a solution it can no longer use, pour that solution into your other hydroponic container. Now leave the solution for those plants to take care off for two months. Once this happens, the solution should be very depleted of nutrients and unable to cause any algae bloom of importance.

Even better, the "waste solution" container, can have plants you can use. For example, you can cultivate herbs with low nutrient requirements that are for indoor use and have them as the "byproducts" of your main hydroponic system. It is also excellent for growing grass for any cattle or horses you may have. (below a picture of papyrus, a plant that naturally deals with solutions with low nutrient concentrations)
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Preparing a Hydroponic Nutrient Solution

2009-02-01T13:18:00.001-08:00

Every hydroponic grower should know how to prepare his or her own solution in order to save money and improve crop results. Preparing a nutrient solution is an exact science involving some basic chemical knowledge that is in fact, not so hard to do. One of the main problems in preparing hydroponics solutions (besides knowing the formulation) is knowing how much to weight of each available nutrient salt in order to achieve the desired concentrations.

In order to solve this problem, you can use the hydroponic nutrient calculator I created called Hydroponic Buddy. The hydroponic calculator is located here.

It is fairly easy to use, the calculator includes links to tutorials you can find within this blog which will tell you how to do many things, from the calculation of simple formulations to the creation of A+B+C concentrated solutions, the copying of commercial nutrients, etc.

And that's it ! Press the calculate button and you'll be shown the final concentration results coupled with the amount of grams you should weight of each salt in order to obtain the concentration results you desire. Now you just need to go to your local supplier and buy each one of the salts in order to prepare your hydroponic solution. This let's you experiment with different nutrient concentrations as well as with recommended and optimum nutrient concentrations for different plant species.

FAQ - Electrical Conductivity (EC) in Hydroponics

2009-02-01T11:53:00.000-08:00

Amongst one of the few properties that hydroponic growers use to control their nutrient solutions is electrical conductivity (EC). The main problem with the measurement of the EC, is that few growers really understand it's meaning and more often than not, grossly overestimate the amount of information it can give them. Therefore, I decided to create this FAQ in order to better explain electrical conductivity, it's limitations and it's uses.

So, what is electrical conductivity ?

Electrical conductivity measures the easiness in which an electrical charge can flow through a certain length of a certain material. It is usually measured in S/cm which just means that the material has a certain conductance in S (Siemens) per centimeter. A material with a higher electrical conductivity let's charge flow more swiftly (it offers less resistance to the movement of charge).

Why is this useful in hydroponics ?

It is useful in hydroponics because the conductivity of a solution is directly proportional to the amount of salts (in this case, the salts are our nutrients) dissolved inside it; so, if a solution has more salts dissolved, it has a higher conductivity. Therefore, measuring EC can give you an idea of how many nutrients are left in your solution.

What are the limitations of EC in hydroponics ?

The first limitation arises because of the chemical character of the property we are measuring. Since EC is proportional to the amount of dissolved salts in each solution, you could suppose that measuring EC would always allow you to calculate nutrient concentrations within your nutrient solution. This is wrong ! Salts increase conductivity but each different ion present inside the solution has a different specific conductivity (they contribute differently to the overall EC) so you could in fact be deceived because you could just have a small amount of an ion that conducts a lot or too much of an ion with a small conductivity. Of paramount importance are the ions that determine pH which have conductivities hundreds of times larger than other ions.

What are some common mistakes when measuring EC ?

Given the above mentioned conditions, EC should always be measured at a constant pH. An EC measured at pH 5 and an EC measured at a pH of 7 will be completely different given that the ions which determine pH have a very large effect on the EC value. Another important fact is that the conductimeter should be calibrated using a solution of known conductivity. If it is not, comparison between measurements can be meaningless.

What is EC useful for ?

The electrical conductivity can tell you if your solution has lost nutrients or water due to evaporation, if measurements are done at the exact same pH value. The EC should be measured when the solution is prepared and three times each day after then. If your solution's EC becomes too high, you can add water to lower it to the original value. If EC becomes too low (70% of original value), you should not add nutrients. This means that your solution has been substantially changed in composition by the plant and it needs to be disposed off and a fresh one needs to be prepared.

Why can't I add nutrients to a solution with low EC ?

You cannot do this because you don't know which nutrients the plant took up. By adding nutrients to the solution you could be putting too much or too little of any given compound. Of course, you could always do some fancy atomic emission analysis to know the exact ionic composition of the solution but the safest (cheapest and easiest) thing would be to adequately dispose of your nutrient solution and start a fresh batch.

Hydroponic Nutrient Solutions for Lettuce

2009-02-01T11:38:00.000-08:00

Most hobby and some commercial hydroponic growers often get their nutrient solutions from stores that sell "generic" hydroponic nutrients. In some cases, this standard solutions are "compensated" with the aid of some additional help coming from additive solutions that are formulated to add certain qualities that the original standard solution is missing.

Well, the sad thing here is that by not preparing his or her own nutrient solution, the hydroponic grower is wasting his main edge in soiless culture. The composition of the nutrient solution.

In the particular case of lettuce, different nutrient solution compositions have varying effects on the plant, this, of course, because the particular chemistry of your nutrient solution must be fitted for your plant in order to achieve optimum results. The use of generic solutions to feed your plants will more often than not end with some loss in product quality (dry weight, nutrient content, marketability, etc).

In a peer reviewed study published in 2004, M.S. Karimaei et al [1] compared different nutrient solutions for lettuce cultivation under hydroponic conditions. Amongst their conclusions, was that the Hoagland solution offers the best conditions for lettuce cultivation amongst the solutions they tested. They also found some important factors such as the electrical conductivity being inversely correlated to dry weight and K concentration. This shows the utmost importance that using the correct and not the "generic" nutrient solution has on your lettuce growing potential.
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[1] Karimaei, M.S., Massiha, S. and Mogaddam, M. 2004. COMPARISON OF TWO NUTRIENT SOLUTIONS’ EFFECT ON GROWTH AND NUTRIENT LEVELS OF LETTUCE (LACTUCA SATIVA L.) CULTIVARS. Acta Hort. (ISHS) 644:69-76

Hydrogen Peroxide in Germination

2009-02-01T08:35:00.000-08:00

As I published earlier, the use of hydrogen peroxide is extensively known in hydroponic cultivation as a disinfectant. However, this little molecule has far more uses and some of them also pertain to plant grow. For example, as it was discussed in the fourth International Symposium on Seed, Transplant and Stand Establishment of Horticultural Crops; Translating Seed and Seedling Physiology into Technology in February 2008, the use of hydrogen peroxide has been studied as an agent to aid the germination of seed.

Indeed, the chemical qualities of hydrogen peroxide make it ideal for the replacement of the stratification of certain seeds. In a peer reviewed article published about the use of hydrogen peroxide for the germination of eastern gamagrass seeds, the authors discovered that the use of hydrogen peroxide 15% for 18 hours indeed helps the seeds germinate by "dissolving" the outer coat of the seeds and therefore facilitating water's access to the seeds embryo.

In fact, hydrogen peroxide is so effective at this, that the above mentioned treatment substitutes a four week period of stratification at 4°C. The seed containing cupules treated with Hydrogen peroxide effectively germinated after only 2 weeks, when such a time was impossible before the treatment. The article mentions that hydrogen peroxide was the "most effective" mean of breaking up seed dormancy and effectively carry out germination. (Below a picture of eastern gamagrass)
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Using Hydrogen Peroxide in Hydroponic Crops

2009-02-01T08:19:00.000-08:00

As we all know, hydroponic growers face the challenge of maintaining pure and innocuous solutions that should be free of any type of bacteria, algae or any other microorganism. The growth of any of these organisms inside the nutrient solution carries with it the imminent possibility of plant disease as well as an increased risk of malnutrition and of course, nutrient deficiencies.

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Algae, in particular, are one of the most troublesome organisms as they are found everywhere and they grow ecstatically inside a hydroponic nutrient solution (after all, they are photosynthetic organisms !). These little creatures love to colonize plant roots (depriving them of food) and also consume a large proportion of the nutrients present inside a hydroponic solution.
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So what should a concerned grower do about the incredible problem of algae growth ? Nature has given us part of the answer in the form of a powerful oxidant called hydrogen peroxide. This molecule, whose formula is basically H2O2 decomposes forming molecular oxygen and water. It also reacts with organic matter in a redox reaction to oxidize it. In other words, algae and hydrogen peroxide cannot coexist.
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However, there is an important problem that arises when using hydrogen peroxide. It does not discriminate between roots and algae so using more than the optimum amount leads to plant root death caused by the same quality that kills algae. So what is this optimum amount ?
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I would love to show you a peer reviewed article that studied this issue but, as a matter of fact, no one has actually studied the levels at which these conditions are right at a scientific level. Most of what we know is currently empirical. Nonetheless, I have - from personal experience- verified that the application of 1mL of hydrogen peroxide (3% v/v) per liter of nutrient solution every week does seem to prevent algae and does not damage plant roots.
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FAQ - Growing media in hydroponics

2009-02-01T08:02:00.001-08:00

In this section I will answer some of the questions that I have already answered in mails that have been sent to me, and that I believe will be helpful to most of the people interested in developing hydroponic crops. This FAQ covers the essential part about the hydroponic growing media and some advice based on my experience and personal knowledge.

What is the aim of the growing media in hydroponic crops and what is it?

The growing media is the substance over which the roots of the growing plants are supported. The plats can grow in either solid support media or simply over water. The function of the growing media in hydroponic crops is totally different from the one achieve by soil in traditional cultivation, because in this case the growing media is just the plants’ mechanical support and it’s not involved in any other growing process.

Which is the ideal growing media for hydroponic crops?

The ideal growing media is the one that can supply the plant’s necessities of air, water and support; the media has to have a favorable interaction with water in order to maintain the humidity for a long time and it also has to have particles big enough to let the air flow and therefore, allow the oxygen to dissolve in the nutrient solution.

The ideal growing media has to be chemically inert for both the nutrient solution and the plant, and it shouldn’t modify neither the pH nor the solution’s nutrient balance. Additionally, the media shouldn’t have a significant reaction with any of the substances excreted by the plant.

The media should also be biologically inert, which means that it shouldn’t contain any organism that might alter the solution’s composition (like algae) or damage the plant (like pathogen micro organisms).

Which growing media are available?

There is a great variety of growing media available in today’s market. The fist criterion to choose a growing media is the kind of plant that will be cultivated. The second criterion is the price, because even though the media isn’t ideal for the plant, the lower price and the fact that it is more available locally are also important. Some of the most popular media are described as follows:

Perlite is a type of amorphous volcanic glass with a high content of water. For this media to be usable in hydroponic crops it has to be heated to 900°C so the water contained in the crystalline structure liberates and therefore the commercial perlite is obtained, also known as expanded perlite. This type of perlite has a great water retaining capacity, leaving enough space for airflow. The size of the particle in this media is also ideal for big plants’ support. The only problem with perlite is the fact that in most of the cases it has to be imported, limiting its use.

Vermiculite is a clay that expands in a limited way with heat. Once expanded, it provides the ideal conditions to be used on hydroponic crops. Nonetheless, this material also has a high cationic exchange capacity which may cause alteration of cation concentrations in the nutrient solution. This could be positive or negative, depending on the hydroponic formulation and on the plant.

Sand is a granular material, generally obtained from any mineral that has been finely divided. This type of material is ideal for hydroponic crops when combined with other materials that can provide a good airflow, because sand by its own can’t provide enough space for airflow and therefore the plants could easily die.

Rice husk is an organic substrate obtained from rice plants. The advantage of this material is that it doesn’t have a fast decomposing, due to its high silicon content. Nonetheless, it has a high water resistance, although it can provide a great airflow. A mixture between rice husk and sand is ideal for hydroponic crops, taking into account that the proportions can vary according to the plant’s necessities. To prevent the rice seed from growing or fermenting and cause a drastic change in the solution’s temperature, it’s important to wet the rice husk before growing the hydroponic plants. The idea is to maintain the rice husk for at least a day under water before using it.

Gravel. The word gravel refers to any mineral or rock which has particles of a size between 5mm and 2cm. Gravel provides an excellent airflow and drain, but a bad water retention. When mixed with sand it could provide an ideal growing media, although it’s also ideal for NTF systems because it doesn’t block pipes or moves as easily as the rice husk does.

How do I choose a growing media?

Choosing the growing media mostly depends on the particular experience. For drop irrigation systems I recommend to use a mixture of rise husk and sand, or to use perlite. For NFT systems I recommend gravel or vermiculite. When choosing a growing media it’s important to take into account the necessities of the plant for it to have the best possible development.

For how long can I use the growing media?

This depends on the nature of the media. Non-organic media such as perlite or gravel can be used many times, while organic media such as rice husk need to be renovated once or twice a year.

What treatment should the growing media receive between different crops?

Between crops the media should be washed with disinfectant. Personally I prefer to use hydrogen peroxide because it can be lately removed by the own plants. The system must be irrigated during a whole day with the hydrogen peroxide solution at 3%. After this, the system must be irrigated for two more days with common water and it will be ready to use again.