UV lights work very well at killing unwanted algae, bacteria, fungus, parasites and other unwanted pests in your pond water. UV clarifiers can kill 90% or more of these unwanted pests while UV Sterilizers have more sterilizing power and can kill 99% or more. Be sure to have the correct size of UV light for your pond. There are several things to take into account such as the size of the pump, the filter, the size and quantity of fish you have and the water volume. Check out our 'How-To' Guide for determining the correct size of UV light for your pond and how to set it up properly.