The Aquascape UltraKlean 3500 Biological Pressure Filter with high-output ultraviolet clarifier and integrated electronic bulb-saver provides pond owners with optimum water conditions and crystal-clear water for ponds up to 3,500 gallons (with a maximum flow rate of 5,200 GPH). The unique sponge-free design minimizes maintenance and maximizes efficient mechanical and biological filtration as the UltraKlean BioBalls create small channels by packing together, leaving behind unwanted debris. The UV clarifier/sterilizer eliminates single-celled algae commonly referred to as green water. The bulb-saver timer feature allows for bulb on/off customization to save bulb life and provides an ideal time to add water treatments while the Simple-to-use self-cleaning feature allows for the unit to be backwashed in less than five minutes without opening the canister or getting your hands dirty. A cleaning indicator light will automatically remind you when the filter requires backwashing. The Aquascape UltraKlean 3500 Pond Filter comes complete with all necessary fittings and is backed by a 3-year limited warranty. Aquascape is passionate about the products we produce, providing unique products, designs, and features that stand above the competition.