The main task of biological filter media is to offer the best colonisation conditions for the bacteria cultures, so that after a short time a bacteria lawn develops. The bacteria feed on dirt particles of all kind and convert substances critical for the aquarium. After the first cleaning process by the mechanical filter media (e.g. EHEIM MECH or MECHpro) the biological filtration is the most important. It provides for clear, healthy water and stabile water values. That’s why we have invested a lot of research work into the development of biological filter media.