The Ultraviolet Sterilizer ("UV Sterilizer") will keep your water clean from the one celled algae that causes the dreaded "Pea Green Soup" curse. When a pond is out of balance, it will experience an explosion of algae cells. The water will turn green as a result of the chlorophyll contained in the cell walls of the algae. A new pond will not have to go through the green stage with a properly sized ultraviolet unit. If a pond already has an algae explosion, a UV Sterilizer will clear the pond in two weeks. However, the UV Sterilizer will not affect the stringy filamentous algae that adheres to the sides of the pond or plant containers. It will only kill the algae that passes through the unit. How a UV Sterilizer works: 1. Algae and bacteria infested water is pumped from the pond to the filter. 2. Water is filtered to remove large debris to enable the UV Sterilizer to work. 3. Water is passed through the UV Sterilizer, which destroys single cell algae after which the clear water is returned to the pond. The UV Sterilizer eliminates an algae explosion in a new pond, clears a current algae explosion, maintains clear and sparkling water, and will allow a new pond to establish and balance much sooner than a pond without a UV sterilizer. All UV Sterilizers are weather resistant.