Aqua One 37s Blue Sponge Pads for CF 500/700 - 2 pack

A new 37s twin pack of blue coarse Aqua One Sponge for the Aqua One CF 500 and Aqua One CF 700 external Canister filter. Open cell foam makes superb water filtration material because it both traps debris and acts as a good home for nitrifying filtration bacteria. Rinse the foam in your filter in some aquarium water only. It is not desirable to get the foam absolutely clean but rather to remove the majority of the waste matter so that water can flow through it easily. After a few months of use and washing the cell structure of the foam starts to collapse and it needs more and more cleaning. This is the time to replace the foam with new pieces.