I've been told that UV only kills 'single cell organisms' not pods and such. Makes sense, but what about ick? I once had ick on a couple of fish, it jumped on all the others and after I put in the UV, the ich never came back.
I wonder if the UV kills ick.
I've been running UV for years. UV is in a way like using a skimmer. You either use it or you don't. The UV bulk does NOT like to be turned on and off as it will burn up the bulb. Once it's on, leave it on and you will have a longer lamp life.
I have never replaced my bulk since the day I bought it. They suggest changing it (I forget how often), but I never did and it still works great. The bulbs are not cheap, but UV is definitely worth using.