Oase Pre Filter Sponge BioMaster

Oase Pre Filter Sponge BioMaster The Pre-filter Foam Set for the BioMaster 250, 350, 600, or 850 and BioMaster Thermo 250, 350, 600, or 850 includes 6 replacement filter foams Customize your choice of filter foam ppi (Pores Per Inch) to meet the needs of your aquarium Timing to replace the pre-filter foam set varies upon aquarium size and the number of fish and plants Color-coded foam: 30 ppi (Coarse) = Orange; 45 ppi (Fine) = Blue