Closed system

Closed system: a hydroponic system, like nutrient film technique (NFT) systems, that recirculates the .
: the scale, described as electrical conductivity (EC) or conductivity factor (CF), that is used to measure the strength of .

The first is a closed system consisting of a double layered container. The seeds sit on a grid through which water drips, being collected in the lower area.

See also: Water, Gardening, Growing, Plant, Light