Mechanical Filter Media
Mechanical Filter Media has one primary use which is to filter out fine particles from the aquarium water that would otherwise remain in suspension or clog up biological media making it less efficient. The most common type of mechanical filter media is bio-foam, a porous, non toxic foam available in grades such as fine, medium & coarse to filter out particles of differing sizes.
Filter wool or floss is also used for the same mechanical trapping of very fine particles and micron bags and socks are available for sump filtration systems. JBL produce a product, Symec Micro for filtering out haze causing micro particles which cannot be collected by other media
Using a mechanical filter media in an external canister filter or sump will remove visible particulates from the water and help create crystal clear water.