This cost effective and durable media removes more particles than other media, effectively trapping debris and small particles into the filter, leaving your water crystal clear. Acurel Polyester Filter Fiber creates fewer gaps for better performance, will not degrade, is easily replaceable, and will complement the performance of any filter.This filter floss is made of 100% polyester, for use in all aquarium filters. Cover the filter carbon with a generous amount of Polyester Filter Fiber fiber. For maximum efficiency, replace fiber and filter carbon when excessive aquarium debris accumulates and fiber appears dirty. Use in fresh and saltwater aquariums.