Pondmaster® 02940 Submersible Ultraviolet Clarifier 40W. Pondmaster® Ultraviolet Clarifiers can be used either fully submerged or out of the water and feature a glowing monitor Halo Ring that shows the clarifier is working submerged or inline. The soft blue Halo is visible during the day or at night from from any angle, but does not detract from the beauty of your pond. Pondmaster Ultraviolet Clarifiers are designed to handle the clarifying needs of ponds up to 6,000 gallons.