Aqua brings you Ultima ll, the next generation of filters and the best tool for Koi ponds. Specifically engineered to meet the environmental demands of ponds.The unique lightweight tubular Bio-Media has low head loss and a very high biofilm surface and is designed for very high flow rates. It protects beneficial bacteria while dislodging unwanted debris. For ponds up to 10,000 gallons. size; 24.5" dia x 42" tall. 8" top opening. 2" inlet and outlet.