Ultra Violet Lights During the spring and summer months algae causes unattractive murky green water. Although this cloudiness can be eliminated with chemicals. The affects of these chemicals are short lived. An Ultra Violet Light and efficient filter is the long-term solution to the clarity problem. The pond water is continuously pumped through a chamber containing an Ultra Violet lamp. The light is surrounded by a quartz sleeve to ensure no water will come in contact with the electric’s. The green algae cells present are penetrated by the Ultra Violet light, destroying their ability to multiply and causing them to band together. The large particles can then be captured in a biofilter leaving the pond water clear. The quartz sleeve is a vital part of the unit as quartz allows the optimum amount of Ultra Violet light through. We do not recommend buying an Ultra Violet lights which do not have a quartz sleeve.