Yea. I had bought some plants for my tank and somehow snails started to appear in the sump. I didn't care because they didn't bother me. After using the uv I started to noticed that the snails are nowhere to be found.
With floor-to-ceiling picture windows and skylights in our living room, our 300 gallon tank is in day light all day. We had a major green water problem. The UV sterilizer very quickly cleared up the green water.