Quick elimination of cloudiness in freshwater and saltwater aquariums and in ponds: reusable foam for the use in filter Easy to use: cut the foam to the size you need (suitable for all filters). Layer as filter stage for pre- and long-term filtering Crystal-clear water: filters off floating algae and all kinds of clouding. Provides very large surface for the settlement of cleansing bacteria No release of harmful substances     water neutral fine foam with 10 ppi pore size Contents: 1 washable foam filter mat for aquariums (50x50 cm) for all types of filter  available in 2.5 cm, 5 cm and 10 cm thickness