Building on the mighty FX performance and reliability platform, the Fluval FX4 high performance Aquarium Canister Filter is the compact 'little brother' to the FX6. The Fluval FX4 bridges the gap between the Fluval FX2 and the FX6 Canister Filter, making it an ideal choice for aquariums up to 1000L. Filter media can easily be placed in a removable stack of media baskets which is at the heart of Fluval's FX multi-stage filtration. The baskets are precision-engineered to eliminate water by-pass, making filtration more efficient. With a total media volume of 3.9 litres the baskets can be stacked in the combination which best suits your aquarium requirements. Each media basket is lined with a foam insert for effective mechanical pre-filtering. The instant-release T-handles make routine maintenance simpler by letting you lift and separate the baskets quickly and easily. The Fluval FX4 also features Smart Pump Technology, which provides optimal filter performance. This advanced technological feature employs an electronic circuit board that continually monitors the pump, to ensure powerful output and energy efficiency. It also manages the filter's unique self-starting feature - just add water then plug and play. To maintain efficiency the Smart Pump will pause on a 12-hour cycle to allow trapped air to escape ensuring the best filtration at all times. At only 41.9 cm in height, the Fluval FX4 fits under most aquariums.