The tanks were part of a recirculating system, reusing water for the rearing of aquatic species. The major principle behind the use of recirculating aquaculture systems is the decrease of consumption of water that can be beneficial in areas of little water flow or in areas where water quality of the overall watershed cannot be influenced by effluent of aquaculture systems. Water parameters of particular interest include nitrogenous compounds, dissolved oxygen, settleable solids and less important parameters. Water quality is of constant evaluation in a recirculating aquaculture system. If water quality parameters reach a high or a low of a given spectrum, fish kills can occur.
Water quality is managed by the components of the recirculating system.
The biofilters use Nitrobacter and Nitrosomonas to break down ammonia produced by the fish and convert it to nitrite and then to harmless, water soluble nitrate. The biofilters also account for some retention of settleable solids. Clarifiers are used as a means to settle fecal material, uneaten food, and flocculants. The management of water quality is of the utmost importance in recirculating aquaculture. In systems that range from six 1 meter tanks to over hundreds of 1 meter and larger tanks, the ability to see and know what is going on with the water quality of the system is important.