The U.V. Steriliser effectively assists in destroying harmful pathogens and algae that may exist within your system especially during the warmer months of the year. A U.V. steriliser is used to control infections by stopping the spread of microorganisms from one fish/coral/invertebrate to another through the water. It is also utilised in pond applications, aquaponic and hydroponic systems in order to control free-floating algae.
When operated correctly, free-floating microorganisms will be killed by the UV light. Note that the organisms must be in the water that flows to the UV steriliser. The Ultra Zap U.V. Steriliser will have no effect on the on the inhabitants that exist within your fish tank, water tank, or fish pond. The UV light has no residual effect and will not kill organisms attached to fish.