These systems can vary in size from a compact portable unit to warehouse-sized buildings. The culture chambers are generally tanks or raceways. Multiple culture chambers may be linked to the remaining components. The effluent from the culture chambers then flows into the settling chambers. Settling chambers are designed to slow water flow to allow particulate matter to settle.
Water then exits the settling chamber and enters the biofilters.
Biofilters remove dissolved metabolites and convert ammonia, which is lethal to fish, to nitrate. A secondary settling chamber may be employed to remove suspended materials that may pass through the biofilter. Upon exiting the biofilters, the flow reenters the culture chambers to complete the loop. Systems which replace water at regular intervals but also recirculate a portion of their water are referred to as semi-closed systems. As a result of small losses of water due to evaporation, leakage, etc.