Aqueon QuietFlow® Canister Filters comes with large media baskets, pre-loaded with media for all three stages of filtration: Foam Pads (mechanical), Carbon (chemical), Bio-Balls and Bio-Ceramic Rings (biological). Designed for both fresh water and saltwater aquariums, the filter media can be arranged to fit any aquarium. Each filter comes with different return fixtures to choose from, traditional Water Director, Spray Bar and a unique hang on the back Polishing Unit. The Polishing Unit allows for the use of one Large Aqueon Filter Cartridge to filter the water on final time before entering the aquarium. The cartridge is quick and easy, taking just a moment to do. With three different size filters, for aquariums up to 155 gallons, Aqueon QuietFlow® Canister Filters were developed by fish enthusiasts to satisfy the needs of fellow hobbyists and their fish tank needs.