Multiple insert filtration system yields more media volume than comparable cartridges. Alternating media replacement preserves bacterial colonies to keep your aquarium clean and your fish healthy. Designed to fit your filter perfectly. Media bags hold media for additional filtration needs. Foam inserts trap debris and house beneficial bacterial colonies. Carbon inserts absorb harmful liquid wastes and dissolved organics. Amrid inserts remove harmful ammonia from freshwater aquariums. Biomax is highly porous ceramic rings the provide maximum surface area for beneficial bacterial growth and helps produce and maintain an active and healthy biological filtration system.