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 rock wool 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
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
Based on techniques used hydroponic systems can be divided in following 6 types:
Wick, Water Culture, Ebb and Flow (Flood & Drain), Drip (recovery or non-recovery),
N.F.T. (Nutrient Film Technique) and Aeroponic. There are hundreds of variations
on these basic types of systems, but all hydroponic methods are a variation (or
combination) of these six.