The only canister diatom filter you'll ever need! Can filter multiple tanks in a jiffy with new easy--start-easy-move valve. ... Designed for continuous use, the Freedom Diatom Filter eliminates the need for other filters. It is a high-speed diatom filter designed to filter aquarium water to an extremely pure state, without disturbing the natural bacteria levels. It uses a unique diatom powder to filter particles as small as one half - one diatom in size. Even some parasites and bacteria are large enough to be trapped and pulled out of the water by a diatom filter. It is a wonderful "green water" cleaner, as free-floating algae is too large to avoid the filter trap., Diatom Filters remove many free-swimming infective stages of various parasites from the tank water before they can attach to their hosts, and when the attached adult parasites on the fish die, the fish are eventually left parasite-free. Because many free-floating bacterias are also removed from the tank, wounded fish often heal more quickly (absent the bacterias that cause infections) After parasites and toxic algae problems have been eliminated, it is a good idea to schedule diatom filtration on a weekly basis or even continuously for a problem tank. Used properly, your Freedom Diatom Filter will eliminate the need to "tear down" your aquarium to clean. It will filter 100% of the water 100% of the time - no hidden "by-pass holes".