Aqua Ultraviolet Sterilizer 160W (Black) 160 Watts (4 x 40 Watt Bulbs) -- 2" Inlet / Outlet The Unit Is Black in Color Max Pond Size if used as a Clarifier = 16,000 Gal -- 9,000 Max GPH Max Pond Size if used as a Sterilizer = 8,500 Gal -- 5,400 Max GPH Rid your pond or water garden of green water guaranteed.