AquaClear BioMax Filter Insert provides an optimal environment for beneficial bacteria growth. Reducing ammonia and nitrite levels, it increases biological filtration efficiency by 30%. Exclusively designed for the AquaClear Filter, the insert is safe for fresh and saltwater aquariums. Available in the following sizes: Filter Insert for AquaClear 20 Filter Insert for AquaClear 30 Filter Insert for AquaClear 70 Filter Insert for AquaClear 110