65 watt Ultraviolet sterilizer eliminates green water.UV sterilization is a proven method for controlling waterborne algae. Combining sterilization with adequate mechanical filtration and operating the two properly is most effective in eliminating algae blooms and maintaining clear water. Practical fish stocking densities and responsible feeding, along with routine filter and UV sterilizer maintenance play a big part in achieving a balanced system. Partial water changes (approximately 10 percent of the pond volume weekly with non-chlorinated water) will aid in diluting nutrients. http://www.emperoraquatics.com/SMARTUV_Instructions_07.pdf