The Classic Series UV?s are ideal for ponds, aquariums, and water features. The Classic?s rugged design has features that allow for quick installation and easy maintenance. Aqua Ultraviolet UV?s will clear your water in 3 to 5 days sometimes overnight and keep it that way. Performance is guaranteed when sized, installed and operated according to our instructions.View Sizing Chart here (PDF)View UVC Instruction Manual here (PDF)