Use the Blagdon Minipond Water Garden Green Water UV Clarifier MPU6000 UVC 9w for effective long term control of green water.The UV Light lamp kills green water algae, this is a chemical free solution that produces no detrimental effects to the environment or water quality.It works by drawing the algae into clumps so that it can be picked up by the filter system.With a 9w power consumption it is economical to run and is also safe and simple to install.It comes complete with a weatherpooof low voltage transformer and is effective in conjunction with all filter systems.Specifically designed for outdoor use. It can be used with any in-pool or external filter for effective control of green water.Minipond Clarifier 6000 stats below *For a shaded pond greater than 75cm/26 operation will be 6000ltrs/1320gal*For a pond in full sunlight operation will be 4500ltr/990gal*For a shallow pond under 75cm/26 operation will be 4500ltr/990gal*For a pond in full sunlight and shallow operation will be 3375ltr/742gal*For a pond with Koi full sunlight and shallow operation will be 1629ltr/371gal*9W*Recommended max flow 3000ltr/660gal*Recommended hose size 25mm/1