The Pondmaster 40 Watt Ultraviolet Clarifier can be used either in-line or submersed. Its black color makes it unobtrusive in any pond application and its unique halo ring design lets you know the product is working. Each unit comes with a 9000 hour long-life UV lamp and water tight quartz sleeve to insure maximum performance. Convenient 1 1/2 inch barbed fittings for quick installation. Can be used with pumps of up to 3000 GPH capacity.