Clarify your water naturally and cultivate bio-filtration with these Polypropylene Bio-balls! They promote gas exchange and increase dissolved oxygen levels, then filter the water as the bio-balls combine with organic waste to dissolve it. Due to the unique geometric design of our bio-balls, the biological loads are maximized within much smaller filter areas. Great for hatcheries, tropical fish farms, koi ponds, waste water systems, cooling towers, and other commercial & industrial systems.