Passive hydroponic systems are simple systems that function without additional energy input. With active hydroponics, additional pumps, aerators, humidifiers or mist sprayers are used. These require additional energy, usually in form of electricity. Although active hydroponics systems are more complex in design, they are much more effective in terms of plant growth due to e.g. the introduction of oxygen.
Simple, passive hydroponic system. A wick system needs no moving parts and no energy. The plant is cultured in a substrate which is supplied with nutrient solution by the capillary action of the wick.
The supply of the plants via the wick is not as effective as with other hydroponic systems. The wick can become blocked by mineral deposits. The disadvantage of this system is that no extra oxygen is supplied to the roots. The system is technically simple but plant growth is slower compared to other active hydroponic systems.
Ebb and flood systems use a pump, which flooded the plant level with nutrient solution. The plants sitting in net pots filled with substrate take up the required amount of nutrient solution. After switching off the pump, the excess nutrient solution is returned to the reservoir via an overflow. A residual amount remains to make the system less vulnerable if the pump should fail.
By raising and lowering the liquid level oxygen is repeatedly introduced, especially in the root area, which leads to very good plant growth. By means of a timer, the ebb-tide rhythm can be adapted best possible to the requirements of the cultivated plants. The system is simple and requires little care.
NFT or nutrient film technique systems are characterized by a permanent flow of nutrients in a thin "film" around the roots. A pump transports the nutrient solution on an inclined plane (e.g. a tube), on which the plant roots lie. They are continuously watered and supplied with nutrients. The constant flow prevents nutrient accumulation.
Owing to the special construction of NFT systems, oxygen is inserted into the nutrient solution, usually through downpipes or vortex systems. In most cases no substrate is used, so that the roots have unhindered access to nutrients and oxygen and can grow quickly.
In deep water culture systems, well-rooted plants are placed in a net pot on a floating plate in the liquid reservoir, like a raft (see also Aztec / "chinampas"). To stabilize the plant, the net pot may be filled with substrate, e.g. clay balls. The roots are hanging directly in the nutrient solution, which is very well oxygenated. This is done by means of an air pump and aeration stones, which introduce very fine air bubbles into the water.
Since the roots are constantly supplied with oxygen-rich nutrient solution, the plants grow very quickly and vigorously. The system is simple and safe, even in the event of a power failure, nothing happens to the plants. Due to the large water reservoir you can leave the system alone for a few days without having to worry about it.
In the Deep Water System, the plants can also sit on a raft and swim on the nutrient solution.
The Deep Flow Technique is a variant of the NFT technique, which is also called Nutrient Flow Technique. Instead of the thin nutrient film, the plants are surrounded by an approximately 4 cm high nutrient solution. The basic procedure is the same. The system is working recirculating.
The deep flow technique makes this type of hydroponic system safer, as the roots are still supplied in the event of a pump failure. However, the method is not applied very often, since especially in longer / larger systems, the supply of oxygen to the plants varies resulting in uneven plant growth.
Via a drip line, the nutrient solution is dripped onto the substrate around the plants. The nutrient solution flows around the roots, so they are directly supplied. The excess fluid drains, drawing oxygen into the root area, which is important for plant growth.
The draining system avoids waterlogging, which is good for root development. Due to the adaptable irrigation frequency, a good fluid intake is achieved, which leads to high yields.
In industrial cultivation, there are often non-recovery systems in use to achieve optimal yield. The plants are always supplied with fresh and equal adjusted nutrient solution. Nothing is circulated, e.g. to avoid the spread of pathogens. However, this process consumes much more water and nutrients get lost.
The nutrient solution is collected and returned to the plants via a pump. By this, resource consumption is much lower. The sprinkling frequency is adapted to the needs of the plants and controlled by a timer.
In an aeroponic farming system, the roots of cuttings or plants do not hang in a liquid but in a mist of nutrient solution. The plants are hung with net pots in a chamber where the roots are sprayed or misted through water nozzles / mist nozzles with nutrient solution.
Aeroponic systems provide the optimal roots supplys with everything they need to grow. Such systems work very effectively and provide maximum plant growth. However, the technical complexity is high because of the high water pressure for the nozzles or nebulizers used. In addition, technical measures must be taken to prevent clogging of the nozzles. The disadvantage is that a failure of the nebulizer is not long time tolerated by the freely hanging roots.
Aquaponics is a term made up of aquaculture (fish farming) and hydroponics (plant breeding), so two cultivation systems are combined. Fish excrements are used to provide the plants with nutrients, they are recycled and used as fertilizer.
The transformation of the excretions into nutrients suitable for plants is done with the help of microorganisms. At the same time a cleaning of the water takes place so that it can be returned to the fish tank and the fish have good living conditions. This creates a cycle with a win-win situation. In addition to growing salad and vegetables, fish are bred as food or ponds are kept clean with ornamental fish.