The Eheim MECHpro mechanical pre-filter media acts as the first dirt barrier when water enters the filter. These specially designed high quality plastic spirals are durable and work well to hold back coarse particles from re-entering your aquarium. While this filter media performs biological water conditioning, residue barely sticks on because of the water-neutral plastic which in turn makes it easy to clean and reuse. This mechanical filter media can be used with freshwater or saltwater aquariums, and is suited for combination with SUBSTRATpro or bioMECH. Sit back and watch how clean the MECHpro keeps your aquarium, keeping you and your aqua life completely satisfied.