(I have 2) These filter are expensive. Due your research! Together or separated. Fluval FX6 is a high performance canister filter with many outstanding features designed to make aquarium fish keeping easier and more convenient than ever. This super capacity yet compact canister filter has a pump output of 925 gallons of water and has a filter circulation of 563 GPH which both work to produce cleaner and healthier results. Filtering material can easily be placed in a removable stack of media baskets which is at the heart of Fluval's multistage filtration. The baskets are precision-engineered to eliminate water by-pass, making filtration more efficient. The baskets can hold a total of 5.9 liters of media and can be stacked in the precise combination of layers that will work best for your aquarium. Each one is lined with a foam insert for effective mechanical pre-filtering. Instant-release T-handles let you lift and separate the baskets quickly and easily, making routine maintenance simpler. Fluval FX6 also features Smart Pump Technology, which provides optimal filter performance. This advanced technological feature employs an electronic circuit board that continually monitors the pump. Impeller speed and force are constantly measured to ensure powerful output and energy efficiency. It also manages the filter's self-starting feature and evacuates air that may enter or build up within the filtration system. On a 12-hour cycle, the pump will pause and allow trapped air to escape, ensuring the best filtration efficiency at all times. Only 21" in height, Fluval FX6 fits under most aquariums.