Deep Flow System
A deep flow system builds upon water culture by increasing oxygenation in the nutrient solution.
An air pump, usually the type sold for aquarium use, powers an air diffuser called an "airstone" to infuse the solution with a fine mist of bubbles. Oxygenation actually occurs at the air/water interface, with the bubbling merely serving to break the surface tension of the liquid.
The oxygen-enriched solution is then pumped to the grow chamber before returning to the reservoir.