Generally speaking, mechanical filter media trap larger dirt particles. Biological filter media, on the other hand, provide the correct conditions for the colonisation of bacteria cultures: the purification bacteria feed off the dirt particles and convert them. Above all, in this way clear, healthy water and stabile water values are arrived at in the aquarium. Our latest development is a combination filter medium, which simultaneously carries out both mechanical and biological functions. EHEIM bioMECH Mechanical-biological filter medium for combined water treatment bioMECH has been cleverly designed: dirt-trapping pockets capture and retain large and small dirt particles. At the same time the subtely designed pore structure provides colonisation for the purification bacteria and thus ensures reliable biological decomposition. The material is pH-neutral and does not contain water hardeners. EHEIM bioMECH is washable and reusable many times over. Specially designed filter medium for simultaneous mechanical and biological water purification The material is pH-neutral and without water hardeners Reusable (wash out carefully, in order not to destroy the bacteria cultures)