State of the art filter media for use in fresh and salt water wet/dry systems. They may be connected together or randomly placed in the filter box. Bio-pin balls help produce turbulence, aiding in the gas-exchange process. The void space between the bio-pins is ideal for the movement of gasses like oxygen and allows it to more-readily come in contact with nitrifying bacteria living on the media surface. Biological filtration is the process by which waste is broken down from toxic ammonia to less toxic nitrates.