Ammonia, feces, and carbon dioxide are not the only waste products in a recirculating fish system. There are also complex organic substances from decomposing feed, urea, fish slime, and metabolic by-products. Added to that are algae, phenols, and a lot of saprophytic bacteria that irrate the fish’s gills, affect growth rate and increase disease susceptibility. These dissolved and suspended materials make up the Biochemical Oxygen Demand (BOD), color, odor, taste, turbidity, etc.. that a foam fractionator can remove.

Foam fractionation works best in saltwater where foam production is easier, but is becoming more popular in freshwater systems when conditions are right.

The process uses air bubbles from a fine bubble diffuser or venturi to create the foam. The foam absorbs and entraps the above pollutants, along with the surface active compounds, all of which are then expelled through a discharge tube or into a holding chamber.