Hydroponic Systems

Hydroponic Systems
Hydroponic systems are characterized as active or passive. An active hydroponic system actively moves the nutrient solution, usually using a pump. Passive hydroponic systems rely on the capillary action of the growing medium or a wick. The nutrient solution is absorbed by the medium or the wick and passed along to the roots. Passive systems are usually too wet and do not supply enough oxygen to the root system for optimum growth rates.

Hydroponic systems can also be characterized as recovery or non-recovery. Recovery systems or recirculating systems reuse the nutrient solution. Non-recovery means just what it says. The nutrient solution is applied to the growing medium and not recovered.
 
The Ebb and Flow System
The Ebb and Flow hydroponic system is an active recovery type system. The Ebb and Flow uses a submersible pump in the reservoir and the plants are in the upper tray. They work on a simple flood and drain theory. The reservoir holds the nutrient solution and the pump. When the pump turns on, the nutrient solution is pumped up to the upper tray and delivered to the root system of the plants. The pump should remain on for about 20 to 30 minutes, which is called a flood cycle. Once the water has reached a set level, an overflow pipe or fitting allows the nutrient solution to drain back into the reservoir. The pump remains on for the entire flood cycle. After the flood cycle the nutrient solution slowly drains back down into the reservoir through the pump.

During the flood cycle oxygen poor air is pushed out of the root system by the upward moving nutrient solution. As the nutrient solution drains back into the reservoir, oxygen rich air is pulled into the growing medium. This allows the roots ample oxygen to maximize their nutrient intake. Rockwool and grow rocks are most commonly used growing mediums in Ebb and Flow type systems. The Ebb and Flow is low maintenance, yet highly effective type of hydroponic gardening.
 
The Wick System
The wick system is a passive non-recovery type hydroponic system. It uses no pumps and has no moving parts. The nutrients are stored in the reservoir and moved into the root system by capillary action often using a candle or lantern wick. In simpler terms, the nutrient solution travels up the wick and into the root system of the plant. Wick systems often uses sand or perlite, vermiculite mix and a growing medium. The wick system is easy and inexpensive to set-up and maintain. Although, it tends to keep the growing medium to wet, which doesn't allow for the optimum amount of oxygen in the root system. The wick system is not the most effective way to garden hydroponically.
Nutrients

Most of the principles that apply to soil fertilizers also apply to hydroponic fertilizers, or nutrient solutions. A hydroponic nutrient solution contains all the elements that the plant normally would get from the soil. These nutrients can be purchased at a hydroponic supply store. Most are highly concentrated, using 2 to 4 teaspoons per gallon of water. They come in liquid mixes or powered mixes, usually with at least two different containers, one for grow and one for bloom. The liquids are the slightly more expensive and the easiest to use. They dissolve quickly and completely into the reservoir and often have an added pH buffer. The powered varieties are inexpensive and require a little more attention. They need to be mixed much more thoroughly and often don't dissolve completely into the reservoir. Most do not have a pH buffer.
pH

Most plants can grow hydroponically within a pH range of 5.8 to 6.8, 6.3 is considered optimal. The pH in a hydroponic system is much easier to check than the pH of soil. Many hardware, pet, and hydroponic supply stores sell pH-testing kits. They range in price from $4.00 to about $15.00, depending on the range and type of test you prefer. Testing pH is easy and essential in a hydroponics system. If the pH is too high or too low the plant will not be able to absorb certain nutrients and will show signs of deficiencies. pH should be checked once a week. It is easy to adjust by adding small amounts of soluble Potash to raise pH, or phosphoric acid to lower pH. There are also several pH meters available. These give a digital reading of the pH in the system. The pH meter cost around $100 and are not necessary in most cases.
 
Nutrient Film Technique
The Nutrient Film Technique or NFT system is an active recovery type hydroponic system. Again, using submersible pumps and reusing nutrient solutions. The NFT uses a reservoir with a submersible pump that pumps the nutrient solution into a grow-tube where the roots suspended. The grow-tube is at a slight downward angle so the nutrient solution runs over the roots and back into the reservoir. The nutrient solution flows over the roots up to 24 hours per day.

Oxygen is needed in the grow-tube so capillary matting or air stones must be used. The plants are held up by a support collar or a grow-basket and no growing medium is used. The NFT system is very effective. Although, many novice hydroponic growers find it difficult to fine tune. It can also be very unforgiving, with no growing medium to hold any moisture, any long period of interruption in the nutrient flow can cause the roots to dry out and the plants to suffer and possibly die.

Hydroponic Gardening

Hydroponic Gardening

The History of Hydroponics
The word hydroponics comes from two Greek words, "hydro" meaning water and "ponics" meaning labor. The concept of soil less gardening or hydroponics has been around for thousands of years. The hanging Gardens of Babylon and The Floating Gardens of China are two of the earliest examples of hydroponics. Scientists started experimenting with soil less gardening around 1950. Since then other countries, such as Holland, Germany, and Australia have used hydroponics for crop production with amazing results.
 
The Benefits of Hydroponics
Hydroponics is proved to have several advantages over soil gardening. The growth rate on a hydroponic plant is 30-50 percent faster than a soil plant, grown under the same conditions. The yield of the plant is also greater. Scientists believe that there are several reasons for the drastic differences between hydroponic and soil plants. The extra oxygen in the hydroponic growing mediums helps to stimulate root growth. Plants with ample oxygen in the root system also absorb nutrients faster. The nutrients in a hydroponic system are mixed with the water and sent directly to the root system. The plant does not have to search in the soil for the nutrients that it requires. Those nutrients are being delivered to the plant several times per day. The hydroponic plant requires very little energy to find and break down food. The plant then uses this saved energy to grow faster and to produce more fruit. Hydroponic plants also have fewer problems with bug infestations, funguses and disease. In general, plants grown hydroponically are healthier and happier plants.

Hydroponic gardening also offers several benefits to our environment. Hydroponic gardening uses considerably less water than soil gardening, because of the constant reuse the nutrient solutions. Due to lack of necessity, fewer pesticides are used on hydroponic crops. Since hydroponic gardening systems use no topsoil, topsoil erosion isn't even an issue. Although, if agricultural trends continue to erode topsoil and waste water, hydroponics may soon be our only solution.

Growing Mediums
The purpose of a growing medium is to aerate and support the root system of the plant and to channel the water and nutrients. Different growing mediums work well in different types of hydroponic systems. A fast draining medium, such as Hydrocorn or expanded shale works well in an ebb and flow type system. Hydrocorn is a light expanded clay aggregate. It is a light, airy type of growing medium that allows plenty of oxygen to penetrate the plant's root system. Both types of grow rocks can be reused, although the shale has more of a tendency to break down and may not last as long as the Hydrocorn. These grow rocks are very stable and rarely effect the pH of the nutrient solution.

Rockwool has become an extremely popular growing medium. Rockwool was originally used in construction as insulation. There is now a horticultural grade of Rockwool. Unlike the insulation grade, horticultural Rockwool is pressed into growing cubes and blocks. It is produced from volcanic rock and limestone. These components are melted at temperatures of 2500 degrees and higher. The molten solution is poured over a spinning cylinder, comparable to the way cotton candy is made, then pressed into identical sheets, blocks or cubes. Since Rockwool holds 10-14 times as much water as soil and retains 20 percent air it can be used in just about any hydroponic system. Although the gardener must be careful of the pH, since Rockwool has a pH of 7.8 it can raise the pH of the nutrient solution. Rockwool cannot be used indefinitely and most gardeners only get one use per cube. It is also commonly used for propagation.

Passive sub-irrigation

Passive sub-irrigation
Passive sub-irrigation is a type of hydroponic growing system where soil is replaced with water and nutrients suspended in solution. Plants growing in hydroponic systems either grow with their roots directly in water or, as in the case of passive sub-irrigation, in moisture-retaining materials such as fiberglass, clay pebbles, coconut husk or perlite. In passive sub-irrigation, the inert medium acts as a wick to carry water from a reservoir below the planting up to the plant's roots. Like conventional hydroponic growing, the water contains all the nutrients the plants need.

Greenhouse Growing

In passive sub-irrigation, plants are grown in porous media that transport water and nutrients to roots. Water is run past the media through a system of pipes, and sits in the bottom of plant-containing trays. Sub-irrigation systems usually exist in controlled environments, because the rate at which nutrients are mixed into the solution is very important. Therefore using sub-irrigation systems outdoors is often difficult, so if you do not have a good indoor space for setting up a sub-irrigation system, it may not be for you.

Expensive Equipment
Another drawback to passive sub-irrigation is that it requires special equipment, the cost of which can be prohibitive when you are first starting up. Although costs vary considerably depending on the type of equipment you buy and how large a setup you desire, it is certainly more expensive than simply planting in the ground. If you already have an indoor hydroponics system, then retrofitting it to become a passive sub-irrigation system may prove less expensive. This means modifying your system so that, instead of suspending plants in water, they are only periodically exposed to it.

Fertilizer Frequency
A disadvantage of all hydroponics systems, including passive sub-irrigation, compared to traditional growing techniques, is the frequency with which you must supply the plants with nutrients. Because they do not have access to soil, which contains many of the minerals and nutrients lacking in water-based growing systems, you must supply it to them in the water. Buying these nutrients is an extra expense over the intermittent fertilization you might give garden plants, though as passive sub-irrigation does recirculate its water, unnecessary loss of nutrients is prevented.

Disease Development
Because passive sub-irrigation waters plants from below, relying on the roots’ capillary action to draw liquid up into the plant, most plants grown in this way are significantly less prone to foliage diseases. However, when insect or disease problems do take root, it is often more difficult to manage them because you cannot simply apply drenches the way you would in the garden. Therefore keeping an eye out for disease is very important, and using integrated pest management strategies becomes even more crucial.

Deep Water Culture

Deep water culture
Deep water culture (DWC) is a hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient-rich, oxygenated water. Bubbleponics is a related method of plant production that involves a top-fed deep water culture system.
 
Traditional methods
Traditional methods favor the use of plastic buckets with the plant contained in a net pot suspended from the center of the lid and the roots suspended in the nutrient solution. An air pump powered aquarium airstone oxygenates the nutrient solution; if sufficiently oxygenated, the plant roots can remain submerged indefinitely. Once the plants are ready to flower, the level of the nutrient solution is gradually reduced to expose the roots to the air.

Plants absorb vastly more oxygen directly from the air than from the oxygen dissolved in water. Deep water culture allows plant roots to absorb large quantities of oxygen while also allowing the uptake of nutrients. This leads to rapid growth throughout the life of the plant.

Recirculation deep water culture
Recirculating direct water culture systems (also known as RDWC) use a reservoir to provide water for multiple buckets. Traditional methods using unconnected buckets require individual testing for pH and conductivity factor (CF). This has led to innovations that have seen the removal of air stones in favor of connecting multiple buckets together and recirculating the water. As the water is reintroduced to the bucket it is broken up and aerated with the use of spray nozzles. Constant recirculating oxygenates the water and ensures a good mix of nutrients CF and stabilizes pH throughout the entire system so testing is required only at one point, which would be at the 'Tub' like reservoir. The deep water culture system requires adequate water + oxygen nourishing solution.

The solution is oxygenated (possibly near, or equal to, oxygen saturation) from an air pump combined with porous stones. With this method the plants may grow faster because of higher amounts of oxygen that the roots receive, versus other forms of deep water culture.
 
Bubbleponics
The term "Bubbleponics" describes a top-fed deep water culture hydroponic system. Basically, the water is pumped from the reservoir up to the top of the roots (top feeding). The water is released over the plant's roots and then runs back into the reservoir below in a constantly recirculating system. As with traditional deep water culture, there is an airstone in the reservoir to help add oxygen to the water. Both the airstone and the water pump run 24 hours a day.

The biggest advantages with Bubbleponics over deep water culture involve increased growth during the first few weeks. With deep water culture, there is a time where the roots haven't reached the water yet. With Bubbleponics, the roots get easy access to water from the beginning and will grow to the reservoir below much more quickly than with a deep water culture system. Once the roots have reached the reservoir below, there is not a huge advantage with Bubbleponics over deep water culture. However, due to the quicker growth in the beginning, a few weeks of grow time can be shaved off.
 
DWC hydroponic system usage
It is advisable to start this type of indoor cultivation with cubes of rock wool. Once the seeds are germinated in cubes of rock wool, put them into the DWC baskets previously filled with expanded clay pellets. Fill the DWC system with water and fertilizers that are hydroponic specific up to the level of the solution in contact with the base of baskets.

In this way, the clay will be in contact with the solution that will be absorbed by the plants roots. Soon the plant will develop a large root system that will naturally immerse in the nutrient solution. It will not be necessary to maintain the level of nutrient solution to the same level of the base of the baskets, but results will come with a lower level. It is recommended replacing the nutrient solution approximately once a week and wash the container / tank with hot water to remove any algae, mold and salt deposits. Every time you fill the tank, measure the pH of the solution and ensure that its appropriate for the plant and growth phase. Revise with the pH indicator. Constantly monitor the pH. The well-oxygenated and enlightened environment promotes the development of algae. It is therefore necessary to wrap the tank with black film obscuring all light.