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.

Fogponics

Fogponics
Fogponics is an advanced form of aeroponics which uses water in a vaporised form to transfer nutrients and oxygen to enclosed suspended plant roots. Using the same general idea behind aeroponics except fogponics uses a 5-10 micron mist within the rooting chamber and as use for a foliar feeding mechanism.

Rotary
A rotary hydroponic garden is a style of commercial hydroponics created within a circular frame which rotates continuously during the entire growth cycle of whatever plant is being grown.

While system specifics vary, systems typically rotate once per hour, giving a plant 24 full turns within the circle each 24-hour period. Within the center of each rotary hydroponic garden is a high intensity grow light, designed to simulate sunlight, often with the assistance of a mechanized timer.

Each day, as the plants rotate, they are periodically watered with a hydroponic growth solution to provide all nutrients necessary for robust growth. Due to the plants continuous fight against gravity, plants typically mature much more quickly than when grown in soil or other traditional hydroponic growing systems. Due to the small foot print a rotary hydroponic system has, it allows for more plant material to be grown per sq foot of floor space than other traditional hydroponic systems.


Substrates
One of the most obvious decisions hydroponic farmers have to make is which medium they should use. Different media are appropriate for different growing techniques.

Expanded clay aggregate
Baked clay pellets, are suitable for hydroponic systems in which all nutrients are carefully controlled in water solution. The clay pellets are inert, pH neutral and do not contain any nutrient value.

The clay is formed into round pellets and fired in rotary kilns at 1,200 °C (2,190 °F). This causes the clay to expand, like popcorn, and become porous. It is light in weight, and does not compact over time. The shape of an individual pellet can be irregular or uniform depending on brand and manufacturing process. The manufacturers consider expanded clay to be an ecologically sustainable and re-usable growing medium because of its ability to be cleaned and sterilized, typically by washing in solutions of white vinegar, chlorine bleach, or hydrogen peroxide (H2O2) and rinsing completely.

Another view is that clay pebbles are best not re-used even when they are cleaned, due to root growth that may enter the medium. Breaking open a clay pebble after a crop has been grown will reveal this growth.

Aeroponics

Aeroponics
Aeroponics is a system wherein roots are continuously or discontinuously kept in an environment saturated with fine drops (a mist or aerosol) of nutrient solution. The method requires no substrate and entails growing plants with their roots suspended in a deep air or growth chamber with the roots periodically wetted with a fine mist of atomized nutrients. Excellent aeration is the main advantage of aeroponics.

Aeroponic techniques have proven to be commercially successful for propagation, seed germination, seed potato production, tomato production, leaf crops, and micro-greens. Since inventor Richard Stoner commercialized aeroponic technology in 1983, aeroponics has been implemented as an alternative to water intensive hydroponic systems worldwide. The limitation of hydroponics is the fact that 1 kg of water can only hold 8 mg of air, no matter whether aerators are utilized or not.

Another distinct advantage of aeroponics over hydroponics is that any species of plants can be grown in a true aeroponic system because the micro environment of an aeroponic can be finely controlled. The limitation of hydroponics is that only certain species of plants can survive for so long in water before they become waterlogged. The advantage of aeroponics is that suspended aeroponic plants receive 100% of the available oxygen and carbon dioxide to the roots zone, stems, and leaves thus accelerating biomass growth and reducing rooting times. NASA research has shown that aeroponically grown plants have an 80% increase in dry weight biomass (essential minerals) compared to hydroponically grown plants. Aeroponics used 65% less water than hydroponics. NASA also concluded that aeroponically grown plants requires ¼ the nutrient input compared to hydroponics. Unlike hydroponically grown plants, aeroponically grown plants will not suffer transplant shock when transplanted to soil, and offers growers the ability to reduce the spread of disease and pathogens. Aeroponics is also widely used in laboratory studies of plant physiology and plant pathology. Aeroponic techniques have been given special attention from NASA since a mist is easier to handle than a liquid in a zero-gravity environment.
 
Passive sub-irrigation
Passive sub-irrigation, also known as passive hydroponics or semi-hydroponics, is a method wherein plants are grown in an inert porous medium that transports water and fertilizer to the roots by capillary action from a separate reservoir as necessary, reducing labor and providing a constant supply of water to the roots. In the simplest method, the pot sits in a shallow solution of fertilizer and water or on a capillary mat saturated with nutrient solution. The various hydroponic media available, such as expanded clay and coconut husk, contain more air space than more traditional potting mixes, delivering increased oxygen to the roots, which is important in epiphytic plants such as orchids and bromeliads, whose roots are exposed to the air in nature. Additional advantages of passive hydroponics are the reduction of root rot and the additional ambient humidity provided through evaporations.

Ebb and flow or flood and drain sub-irrigation
In its simplest form, there is a tray above a reservoir of nutrient solution. Either the tray is filled with growing medium (clay granules being the most common) and planted directly or pots of medium stand in the tray. At regular intervals, a simple timer causes a pump to fill the upper tray with nutrient solution, after which the solution drains back down into the reservoir. This keeps the medium regularly flushed with nutrients and air. Once the upper tray fills past the drain stop, it begins recirculating the water until the timer turns the pump off, and the water in the upper tray drains back into the reservoirs.

Run to waste
In a run-to-waste system, nutrient and water solution is periodically applied to the medium surface. This may be done in its simplest form, by manually applying a nutrient-and-water solution one or more times per day in a container of inert growing media, such as rockwool, perlite, vermiculite, coco fibre, or sand. In a slightly more complex system, it is automated with a delivery pump, a timer and irrigation tubing to deliver nutrient solution with a delivery frequency that is governed by the key parameters of plant size, plant growing stage, climate, substrate, and substrate conductivity, pH, and water content.

In a commercial setting, watering frequency is multi factorial and governed by computers or PLCs.

Commercial hydroponics production of large plants like tomatoes, cucumber, and peppers use one form or another of run-to-waste hydroponics.

In environmentally responsible uses, the nutrient rich waste is collected and processed through an on site filtration system to be used many times, making the system very productive.

The majority of bonsai are now grown in soil-free substrates (typically consisting of akadama, grit, diatomaceous earth and other inorganic components) and have their water and nutrients provided in a run-to-waste form.

Deep water culture
The hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient-rich, oxygenated water. Traditional methods favor the use of plastic buckets and large containers with the plant contained in a net pot suspended from the centre of the lid and the roots suspended in the nutrient solution. The solution is oxygen saturated by an air pump combined with porous stones. With this method, the plants grow much faster because of the high amount of oxygen that the roots receive.


Top-fed deep water culture
Top-fed deep water culture is a technique involving delivering highly oxygenated nutrient solution direct to the root zone of plants. While deep water culture involves the plant roots hanging down into a reservoir of nutrient solution, in top-fed deep water culture the solution is pumped from the reservoir up to 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 deep water culture, there is an airstone in the reservoir that pumps air into the water via a hose from outside the reservoir. The airstone helps add oxygen to the water. Both the airstone and the water pump run 24 hours a day.

The biggest advantage of top-fed deep water culture over standard deep water culture is increased growth during the first few weeks. With deep water culture, there is a time when the roots have not reached the water yet. With top-fed deep water culture, 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 top-fed deep water culture over standard deep water culture. However, due to the quicker growth in the beginning, grow time can be reduced by a few weeks.

History of Hydroponics

History
The earliest published work on growing terrestrial plants without soil was the 1627 book Sylva Sylvarum by Francis Bacon, printed a year after his death. Water culture became a popular research technique after that. In 1699, John Woodward published his water culture experiments with spearmint. He found that plants in less-pure water sources grew better than plants in distilled water. By 1842, a list of nine elements believed to be essential for plant growth had been compiled, and the discoveries of the German botanists Julius von Sachs and Wilhelm Knop, in the years 1859-65, resulted in a development of the technique of soilless cultivation. Growth of terrestrial plants without soil in mineral nutrient solutions was called solution culture. It quickly became a standard research and teaching technique and is still widely used today. Solution culture is now considered a type of hydroponics where there is no inert medium.

In 1929, William Frederick Gericke of the University of California at Berkeley began publicly promoting that solution culture be used for agricultural crop production. He first termed it aquaculture but later found that aquaculture was already applied to culture of aquatic organisms. Gericke created a sensation by growing tomato vines twenty-five feet high in his back yard in mineral nutrient solutions rather than soil. He introduced the term hydroponics, water culture, in 1937, proposed to him by W. A. Setchell, a phycologist with an extensive education in the classics. Hydroponics is derived from neologism constructed in analogy to  geoponica, that which concerns agriculture, replacing, earth, with water.

Reports of Gericke's work and his claims that hydroponics would revolutionize plant agriculture prompted a huge number of requests for further information. Gericke had been denied use of the University's greenhouses for his experiments due to the administration's skepticism, and when the University tried to compel him to release his preliminary nutrient recipes developed at home he requested greenhouse space and time to improve them using appropriate research facilities. While he was eventually provided greenhouse space, the University assigned Hoagland and Arnon to re-develop Gericke's formula and show it held no benefit over soil grown plant yields, a view held by Hoagland. In 1940, he published the book, Complete Guide to Soil less Gardening, after leaving his academic position in a climate that was politically unfavorable.

Two other plant nutritionists at the University of California were asked to research Gericke's claims. Dennis R. Hoagland and Daniel I. Arnon wrote a classic 1938 agricultural bulletin, The Water Culture Method for Growing Plants Without Soil,. Hoagland and Arnon claimed that hydroponic crop yields were no better than crop yields with good-quality soils. Crop yields were ultimately limited by factors other than mineral nutrients, especially light. This research, however, overlooked the fact that hydroponics has other advantages including the fact that the roots of the plant have constant access to oxygen and that the plants have access to as much or as little water as they need. This is important as one of the most common errors when growing is over- and under- watering; and hydroponics prevents this from occurring as large amounts of water can be made available to the plant and any water not used, drained away, recirculated, or actively aerated, eliminating anoxic conditions, which drown root systems in soil. In soil, a grower needs to be very experienced to know exactly how much water to feed the plant. Too much and the plant will not be able to access oxygen; too little and the plant will lose the ability to transport nutrients, which are typically moved into the roots while in solution. These two researchers developed several formulas for mineral nutrient solutions, known as Hoagland solution. Modified Hoagland solutions are still used today.

One of the earliest successes of hydroponics occurred on Wake Island, a rocky atoll in the Pacific Ocean used as a refuelling stop for Pan American Airlines. Hydroponics was used there in the 1930s to grow vegetables for the passengers. Hydroponics was a necessity on Wake Island because there was no soil, and it was prohibitively expensive to airlift in fresh vegetables.

In the 1960s, Allen Cooper of England developed the Nutrient film technique. The Land Pavilion at Walt Disney World's EPCOT Center opened in 1982 and prominently features a variety of hydroponic techniques. In recent decades, NASA has done extensive hydroponic research for their Controlled Ecological Life Support System or CELSS. Hydroponics intended to take place on Mars are using LED lighting to grow in different color spectrum with much less heat.

Origin
Soilless culture
Gericke originally defined hydroponics as crop growth in mineral nutrient solutions. Hydroponics is a subset of soilless culture. Many types of soilless culture do not use the mineral nutrient solutions required for hydroponics.

Plants that are not traditionally grown in a climate would be possible to grow using a controlled environment system like hydroponics. NASA has also looked to utilize hydroponics in the space program. Ray Wheeler,a plant physiologist at Kennedy Space Center’s Space Life Science Lab, believes that hydroponics will create advances within space travel. He terms this as a bioregenerative life support system.

Techniques
The two main types of hydroponics are solution culture and medium culture. Solution culture does not use a solid medium for the roots, just the nutrient solution. The three main types of solution cultures are static solution culture, continuous-flow solution culture and aeroponics. The medium culture method has a solid medium for the roots and is named for the type of medium, e.g., sand culture, gravel culture, or rockwool culture.

There are two main variations for each medium, sub-irrigation and top irrigation. For all techniques, most hydroponic reservoirs are now built of plastic, but other materials have been used including concrete, glass, metal, vegetable solids, and wood. The containers should exclude light to prevent algae growth in the nutrient solution.

Static solution culture
In static solution culture, plants are grown in containers of nutrient solution, such as glass Mason jars (typically, in-home applications), plastic buckets, tubs, or tanks. The solution is usually gently aerated but may be un-aerated. If un-aerated, the solution level is kept low enough that enough roots are above the solution so they get adequate oxygen. A hole is cut in the lid of the reservoir for each plant. There can be one to many plants per reservoir. Reservoir size can be increased as plant size increases. A home made system can be constructed from plastic food containers or glass canning jars with aeration provided by an aquarium pump, aquarium airline tubing and aquarium valves. Clear containers are covered with aluminium foil, butcher paper, black plastic, or other material to exclude light, thus helping to eliminate the formation of algae. The nutrient solution is changed either on a schedule, such as once per week, or when the concentration drops below a certain level as determined with an electrical conductivity meter. Whenever the solution is depleted below a certain level, either water or fresh nutrient solution is added. A Mariotte's bottle, or a float valve, can be used to automatically maintain the solution level. In raft solution culture, plants are placed in a sheet of buoyant plastic that is floated on the surface of the nutrient solution. That way, the solution level never drops below the roots.

Continuous-flow solution culture
In continuous-flow solution culture, the nutrient solution constantly flows past the roots. It is much easier to automate than the static solution culture because sampling and adjustments to the temperature and nutrient concentrations can be made in a large storage tank that has potential to serve thousands of plants. A popular variation is the nutrient film technique or NFT, whereby a very shallow stream of water containing all the dissolved nutrients required for plant growth is recirculated past the bare roots of plants in a watertight thick root mat, which develops in the bottom of the channel and has an upper surface that, although moist, is in the air. Subsequent to this, an abundant supply of oxygen is provided to the roots of the plants. A properly designed NFT system is based on using the right channel slope, the right flow rate, and the right channel length. The main advantage of the NFT system over other forms of hydroponics is that the plant roots are exposed to adequate supplies of water, oxygen, and nutrients. In all other forms of production, there is a conflict between the supply of these requirements, since excessive or deficient amounts of one results in an imbalance of one or both of the others. NFT, because of its design, provides a system where all three requirements for healthy plant growth can be met at the same time, provided that the simple concept of NFT is always remembered and practised. The result of these advantages is that higher yields of high-quality produce are obtained over an extended period of cropping. A downside of NFT is that it has very little buffering against interruptions in the flow, e.g., power outages. But, overall, it is probably one of the more productive techniques.

The same design characteristics apply to all conventional NFT systems. While slopes along channels of 1:100 have been recommended, in practice it is difficult to build a base for channels that is sufficiently true to enable nutrient films to flow without ponding in locally depressed areas. As a consequence, it is recommended that slopes of 1:30 to 1:40 are used. This allows for minor irregularities in the surface, but, even with these slopes, ponding and water logging may occur. The slope may be provided by the floor, or benches or racks may hold the channels and provide the required slope. Both methods are used and depend on local requirements, often determined by the site and crop requirements.

As a general guide, flow rates for each gully should be 1 liter per minute. At planting, rates may be half this and the upper limit of 2 L/min appears about the maximum. Flow rates beyond these extremes are often associated with nutritional problems. Depressed growth rates of many crops have been observed when channels exceed 12 metres in length. On rapidly growing crops, tests have indicated that, while oxygen levels remain adequate, nitrogen may be depleted over the length of the gully. As a consequence, channel length should not exceed 10–15 metres. In situations where this is not possible, the reductions in growth can be eliminated by placing another nutrient feed halfway along the gully and halving the flow rates through each outlet.