Aqua One Sponge Pad AquaStart 340 Pro 69cThe Aqua One 69s Sponge pad is a rinsable green filter foam block for use in the AquaStart 340 Pro aquarium. The foam block is the first stage of the filtration process and traps larger debris and cultures helpful areobic filtration bacteria. The sponge black should be removed and rinsed in a little aquarium water ( not tap water) when blocked with fish waste and debris. This will usually be every four to six weeks. After several months the foam cell structure begins to break down and the block should be replaced.