Ultraviolet Lights to Get Rid of Algae
UV clarifiers use ultraviolet light to control and eliminate algae and disease organisms in garden ponds. If you have goldfish or Koi in your garden pond, a UV clarifier is a definite requirement in order to keep your fish healthy, well-fed and comfortable. UV sterilizers are often mistaken for UV clarifiers. Although both pieces of equipment have the same purpose, a UV sterilizer is a more powerful algae killer than a UV clarifier.
Neither UV clarifiers nor UV sterilizers kill the beneficial bacteria that grow on rocks or in the filter. This beneficial bacterium is necessary to fertilize pond plants for the fish to consume. Beneficial bacteria are also essential to the health of other pond occupants including frogs, water snails, plants and other fish. When Koi and goldfish excrete they create fish waste; which turns into deadly ammonia. The beneficial bacteria convert deadly ammonia into harmless nitrates and nitrogen; which in turn is responsible for fertilizing pond plants.
Beneficial bacteria helps maintain a healthy fish population, but too much beneficial algae can accumulate in the pond and send it off balance if a UV clarifier or sterilizer isn't used to filter it out. A high accumulation of algae typically occurs as the pond water warms up in the spring.
Generally, the UV clarifiers need to be sized correctly and have a pre-filter to catch all of the large debris. You can purchase clarifiers which fit onto your pond pump directly, but do your homework before you buy to ensure this is possible. There are submergible and non-submergible varieties. Make sure you get a UV clarifier that is compatible with the rest of your pond system. Most times you do not need to run the clarifiers 24/7; you can find some that only need to be run when there is an algae problem. You need to clean it about every 3 to 5 days when in use or whatever the manufacturer recommends.
UV clarifiers are available for approximately $159 online for ponds that hold up to 500 gallons. UV clarifiers can cost up to $1150 for ponds that hold up to 15,000 gallons of water. Replacement bulbs, which should last up to a year or 8000 hours, cost about $40 - $90.