A
hydroponic system allows for the growth of plants without soil. Such
a system may be set up in several different ways. Some of these ways
require a medium to provide stability for the plants, such as gravel.
Others do not.
An ebb and flow hydroponic system is an example of a medium-based method.
In it, the plant is placed within a medium within a tray. This tray
is regularly flooded with water and nutrients for plant health.
A common hydroponic system which does not use a medium is the Nutrient
Film Technique (NFT). This method involves placing plants within sloping
channels. The liquid solution is regularly pumped up to the top of this
incline. Gravity runs it downwards over plant root systems. The water
and mineral solution is then drained and recycled.