I personally don't run UV and have been told not to by LFS owners many times. I was always told, and have read that they are a waste of money. The amount of water going through them does not necessarily cycle the entire tank properly. As in it works so slowly to actually sterilize every water molecule that an infection in the tank can actually continue to reproduce in the tank faster than the sterilizer can kill it off. Another moot point is that the lens gets mucky so quickly that it prevents the rays from doing their job. Only one company makes a unit that has a wiper to clean the lens. Tis better and cheaper to buy only quality livestock, keep the filters clean and do plenty of water changes. Basically keep the fish happy and healthy and everything else should fall into place. I think of UV sterilizers as a bandaid for a larger problem. Go into an lfs and tell them you have a green water problem. So the guy tells you to buy a UV sterilizer to kill the algae spores. HHmmm... Sounds like the guy only wanted to sell something instead of walking you through your tank to find the root of the problem and fix that instead.