The prefilter sponge is designed for hang-on back filters or external filter inlets. Adding a pre-filter sponge adds to your filtration capacity and extends the life of media in your filter. By filtering out food, small fish, snails, and debris, filter media like Purigen and fine filter pads last longer.

Sponges are designed as well to protect small fishes and shrimps to be sucked into the filter chamber.

The small sponge fits a small 9mm-12mm inlet pipe.