Note
In closed and semi-closed culture systems, water must be treated before it can be recycled into the primary growing tanks and raceways. The nature and degree of treatment is a function of the water quality leaving the growing area, the desired water quality after treatment, and of course the economics of the treatment compared to the benefits. "Treatment" can mean many different things; it may mean aeration, addition of a chemical or drug, degassing, disinfection or filtration.