Please note : This media currently being used in eggcrate structures in marine sumps sera siporax is a fully biological filter material for almost all filters. 1 liter sera siporax pond provides as much settling area for bacteria as, approximately 34 liters of clay filter material. Prefilter with sera biofibres coarse to prevent large particles from entering the biofilter. sera siporax provides bacteria an extremely large amount of open-pored tunnel structures. This allows an ideal supply of the bacteria with nutrients and a smallest amount of fresh water. There are oxygen-poor conditions within the tunnels. This makes the bacteria crack nitrate to get enough oxygen. Consequently, they continuously break down nitrate, and the water remains low in nitrate. The surface of one liter of sera siporax Professional has almost as much biological breakdown power as 34 liters of clay filter material.