Originally Posted by Ouch
Would a UV light kill the beneficial bacteria in a cycled tank or am I confusing it with something else? (which is a possibility with me lol)
Since beneficial bacteria are sticky and adhere to all the surface areas, in the top layer of the substrate and in the filter media-very little are in the water column. A UV light won't hurt your nitrogen cycle since they are designed to destroy things in the water column as they pass through the UV light.