AquaMiracle Aquarium Filter Replacement Sponge, Fish Tank Filter Replacement Parts, Including 2 x Coarse Sponge, 2 x Fine Sponge & 4 x Carbonized SpongePACKAGE INCLUDES 2 x coarse sponge, 2 x fine sponge & 4 x carbonized sponge. COARSE SPONGE Filters out large size impurities such as food residue, fish excrements, plant leaves, etc. Recommend to replace once every 2 months. CARBONIZED SPONGE Removes odor, chlorine and fine particles. Recommend to replace once every month. FINE SPONGE Polishes water before it goes back to the tank. Recommend to replace once every 2 months. ROUTINE CLEANING Depending