External Filtration Tailored to Your Aquarium and Budget Not all canister filters are built the same. Some are basic designs with three media trays, while others are more complex with five stages of filtration including add-on features like UV sterilization. One aspect that's true of all canister filters is that they hold more media than internal filters and are great for larger tanks or tanks with a lot "messy" creatures. truAqua will always give you a wide selection of these popular filters at the best prices guaranteed! We'll also give you great customer support on canister filters and all the aquatic supplies we offer.