Whether or not it is good or bad for a reef tank is still under much debate. I am considering getting a UV sterilizer myself and after searching this site for information about them have still come to no conclucion. Some people swear by them and others swear against them. I think for fish only it is undisputed that they don't cause any harm. However, many hobbyists believe that using UV on a reef tank with filter feeders will drastically reduce the plankton availabe for the filter feeders. I am definitely going to get one for my attempt at raising dottyback fry, but I haven't decided yet for the reef tank. I will post back if I find a good source of information. I did notice that many of the tanks in the book, Ultimate Marine Aquariums, 19 of the 50 tanks had UV sterilizers and another 4 had ozone devices without a UV sterilizer. But, there were another 7 or 8 tanks that didn't even run a protien skimmer. Those tanks had large refugiums for nutrient export and major water changes. Not sure if I really helped out at all, but there are many hobbyists that are successful with and without a UV sterilizer.