OASE BioMaster 20ppi Ultra Coarse Replacement Filter Foam

The 20 ppi Replacement Filter Foam for the BioMaster 250, 350, or 600 includes an ultra-coarse replacement filter foam. The combination of coarse and fine filter foams allows you to customize to meet the filtration needs of your aquarium. Timing to replace the filter foam varies upon aquarium size, number of fish and plants, and declines in filter performance.