The Aqueon QuietFlow 20/75 Phosphate Reducing Specialty Aquarium Filter Pad will keep your aquarium nice and clean for your fish. Designed for use with the Aqueon QuietFlow 20 or QuietFlow 75 LED Pro Power Filters, these pads are pre-cut for easy installation and come in a handy pack of four. The phosphate-removing pads filter out excess phosphate to control algae growth and also trap excess waste, food and organic debris for clearer water. Replace them every two to three weeks for happy, healthy fin-buddies!