Start filtering phosphate from your favorite aquarium with the Seapora Phos Pad from Underwater Treasure! Troublesome algae feasts on phosphate making it public enemy #1 for aquarium owners everywhere. This dense， chemical filter pad works for both freshwater and marine applications， and can be shaped to fit any filtration system—including canister filters， hang-on filters， trickle filters， pond filters， wet-dry filters—and filter cartridge frames.