The Penn-Plax Cascade Aquarium Canister Filter is an external filter that helps you meet a wide array of your aquarium's filtration needs. It delivers powerful mechanical， chemical and biological filtration by combining the benefits of several types of filter media—all with one， handy canister filter. Each pump comes with large filter trays， startup filter media and input/output tubing so you can begin filtering right away. The large filter trays mean you can use more media， including Bio-Floss， Bio-Sponges， activated carbon and any combination you'd like. With a push-button primer， two 360-degree rotational valve taps， flow-rate control valves and hose clamps， this filter is easy to start and adjust. After just one day， you should see visible improvement in your tank’s water quality.