Nutrient Film Technique.
The purist form of today’s highly developed hydroponic growing systems is Nutrient Film Technique (N.F.T.). It is also the form of hydroponics most intriguing to the public because of its futuristic nature and appearance. The nutrient is fed into growtubes where the roots draw it up. The excess drains by gravity back to the reservoir. A thin film of nutrient allows the roots to have constant contact with the nutrient and the air layer above at the same time.
Drip-Irrigation or Micro-Irrigation
Today’s greenhouse irrigation systems employ, to an ever-increasing extent, the concept of drip or microirrigation. It entails a principle of minimized water consumption with maximized plant benefit. There are literally hundreds of emitting/dripping/trickling/micro-spraying/etc. devices on the market today for the commercial/hobbyist grower to choose from. A submersed pump feeds nutrients solution through header tubes to secondary feed lines connected to drip emitters. A controlled amount of solution is continuously drip-fed over the medium and root system. Another tube is connected to the lower part of the garden system to recover the solution.
Aeroponics / Deep Water Culture
Plant roots are suspended in highly oxygenated nutrient solution allowing easy inspection and pruning of roots. Air pumps, compressors or Oz injectors provide oxygen which is crucial to healthy plant growth. The simplicity and affordability of these very active systems make them popular with home hobbyists and commercial growers alike.
In an Aeroponic system the roots are misted within a chamber. A pump pushes the water with nutrient solution through sprayers, keeping the roots wet while providing a maximum amount of oxygen.
This technique is an excellent way to propagate cuttings.
Deep Water Culture is another form of aeroponics. The root system of a plant grown in Deep Water Culture is immersed in water with a bubbling aerator keeping the roots oxygenated.
This technique is very good to use with plants that are heavy feeders.
Flood & Drain
Flood & Drain systems are similar to N.F.T. systems. They are ideal for multiple plant per square foot growing where individual plant inspection is difficult. They are also very popular as propagation tables. A plastic growing tray is flooded periodically by a submersed pump connected to a digital timer (or the ControlFreak!). Medium and root system are soaked, then drained (via gravity back through the pump) at
specific intervals. Various mediums can be used, Rockwool is the most popular with Flood & Drain systems.
The Ebb & Flow trays are examples of the Flood & Drain system.
Home Hobbyist Systems
There are a number of compact hydroponic systems and kits most popular with home hobbyists, researchers and teachers. These are made to be especially attractive to children in order to get their attention and interest. Hobby systems include deep water and aeroponic systems which are scaled down versions of commercial systems.
Passive Planters / Hydroculture
This is probably the most commonly know form of hydroponics. These systems do not require a water or air pump and are therefore called passive systems. Passive Planters have been used in office buildings and restaurants for many years.
Hydroculture planters utilize a clean, porous growing medium to support plant roots. A nutrient reservoir in the base of the growing container allows the plants to take as much or as little water as they require. Water level indicators show exactly when and how much to water. Clean, odourless and non-allergenic, hydroculture or passive planters are ideal for every environment.