The original sera siporax is suitable for use in both freshwater and marine aquariums as well as in ponds. Not depending on the kind of filter (internal/external/trickle filter) it maximizes the surface required for biological purification and provides the optimal substrate for the settling of necessary filter bacteria. The sera filter biostart included with the kit contains purification bacteria which activate sera siporax biologically immediately upon addition and start pollutant breakdown in the water.