Anjon Super Nova Exstream UV Sterilizers are high intensity, light emitting UV clarifiers have an outstanding effect in eliminating free floating algae and fish diseases to create exceptionally healthy water features Anjon Super Nova Extream UV Clarifiers are the perfect addition to any Koi pond or water garden. These quality units ensure clear water, allowing the pond owner to easily view their pond fish. UV Clarifiers emit radiation in the form of ultraviolet light in a confined environment. Their purpose is to eliminate free-floating organisms from pond water. UV Clarifiers control algae growth by by nullifying small protozoa, fungi and viruses which active algae needs to feed on to survive. UV Clarifiers are not filters in the sense that they detoxify the water. Their purpose is to kill the unicellular algae which are mainly responsible for green water. Basically a UV consists of a tube within a tube. The water flows through an outer tube and over the UV lamp that is housed in the inner tube.