Filter mass The Eheim MECHpro is a pre-filter compound also for small dirt particles and biological processing. The spiral shape ensures that even small dirt particles are retained. The high-quality, absolutely water-neutral plastic enables easy and residue-free cleaning. The surface structure nevertheless allows colonisation with cleaning bacteria and is therefore also a biological water treatment. MECHpro is ideally suited for combination with SUBSTRATpro or bioMECH. Mechanical filter media retain suspended matter and dirt particles. This happens in different stages: At the beginning, before the water goes through the further cleaning process, the pre-filter masses EHEIM MECH and EHEIM MECHpro prove their worth. EHEIM FIX is suitable as a separating layer between mechanical and biological filter media. And for fine filtering at the end, before the water enters the aquarium again, the filter wool EHEIM SYNTH is ideal.