I bought a UV after a problem with Ich in one of my tanks. So one of my tanks has one and the other doesn't.
Only one Yellow Tang got the Ich and after getting rid of the Ich on the Tang and moving the other fish (who never got it) I dropped the salinity on this tank and started with the Sterilizer and left for the six week period you needed to do to get through the Ich cycle.
I then put my stock back in the tank. During the six week process I found this product from TLC. It has good bacteria basically in the bottle. In addition to using the TLC I use Kent's Essential Elements. Essential Elements has always been used by me and with a sterlizer in this tank, a dose of it regualry wouldn't hurt. So far, so good... and we are talking several months.
Since incorporating the TLC into the sterlized tank plan I have noticed little change in my water quality from a visual standpoint and no harmful or detrimental changes in water parameters.
Also, everyone is alive and healthy and no one has died or caught a disease for that matter.
So that is my experience with the UV. I like it and my LFS has ordered another one for me for the second tank.
Denise M.