TMC Pond Clear UV ~ Pond Clear works by halting the reproduction of algae. The ultraviolet radiation at a wavelength of 254 nanometers is extremely effective in doing so. The ultraviolet lamp is sealed inside a quartz sleeve. As water is pumped through the unit, ultraviolet light from the lamp destroys the green, single celled water borne algae (which makes garden ponds murky and unattractive), It will leave the water crystal clear. It has no adverse effect on sensitive plant and pond life.