UV sterilizers

There are many threads on here about UV sterilizers, but many mixed responses about if they are worth it or not. I know I've read that they are not efficient enough to make them worth while, but tonight I was at my LFS and was talking to the owner of the store (which I've never done one on one before) and he was asking me about my tank. For those who don't know my tank, it is a 240 gallon 8ft long display tank attached to a 75 gallon sump attached to a 40B refugium / filter feeder tank, total capacity is about 300 gallons. I was interested in buying a one spot foxface, he asked what I plan to keep in my tank and I told him I have a bunch of little fish on my list, but eventually I plan to have a yellow tang, powder blue tang, and regal tang in the tank. So he asked if I was running a UV sterilizer on the tank, I told him no because I had read that they weren't worth it because they weren't powerful enough to make a difference with the little amount of time that lights are in contact with the water. He said he would highly recommend one before I purchase the tangs, and his main reason was that he said it will help kill off ich. He told me they had a huge tank at one of the local restaurants that was full of tangs that they had a lot of problems with ich and the only way to fix it was with the UV sterilizer, and said especially having the powder blue tang, if you look at it funny it will get ich. I haven't had an issue with ich up until now, but I don't have easily stressed fish yet so here I am trying to get more feedback. He also said in fish only systems its not such a big deal, but in reef tanks inverts are carriers that can easily cause problems for the fish. He said they carry a 57W UV sterilizer that he would recommend for my size system.



If you do run a UV sterilizer, how big of a tank do you have, how big of a UV sterilizer do you use, and what benefits do you feel you gain from running a UV sterilizer to justify the costs? If you have made a choice to not run a UV sterilizer why do you feel you don't need one?