Danner® Submersible Ultraviolet Clarifier 10 Watt Ultraviolet Clarifier Pondmaster Ultraviolet Clarifiers safely control free-swimming "suspended" algae without the use of any chemicals or water treatments. The UV helps maintain crystal clear water in your pond by passing it in a spiral motion across the UV Lamp mounted inside the housing, greatly reducing the algae levels in your pond. Suitable for small ponds.