The Filter Set contains 1 x Poly Pad (5) Change pad once a week to ensure maximum filtration 1 x Carbon Sponge (2) Recommended to replace sponge every 4 weeks 1 x Filter Sponge coarse Clean or replace sponge every 3 months 1 x Filter Sponge fine Clean or replace one sponge at a time every 9 -12 months Poly Pad Poly Pads are designed to absorb larger particles of dirt in the water. When the particles are caught by the pads they are prevented from obstructing the growth of water-cleansing bacteria. Carbon Sponge The carbon sponge cleans the water from chemical pollution by binding these substances & preventing their release back into the water. In order to utilise the full effectiveness of the activated carbon this sponge should be changed every four weeks or more often if you have large or strongly burrowing fish. Filter Sponge Coarse & Fine The filter sponges contain bacteria which effectively clean the water. We recommend carefully cleaning one sponge at a time with warm water every 3-6 months or replacing it. Only one sponge at a time should be replaced in order to maintain the biological balance in the aquarium.