A new Aqua One Sponge insert for Aqua Nano (new version that accepts slide in Filter Cartridges). 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 moths 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 a new piece.
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