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.

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 prove 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 ?

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.

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.

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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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).

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.

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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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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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 .

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 2×2 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).