[BigOldReef]

Several years ago I added a UV system to my reef. I added a large volume system Dual 54w 30" Tubes plumbed for 2".

I got it as an insurance policy, at the time the system was doing really well. I can't say that I noticed any differences. There was definitely no negative changes in the system. However, please be aware that in a healthy properly balanced reef, the efficiency of the UV is constantly decreasing because the UV tubes are constantly getting calcified.

So if you are considering this, make sure you find a unit that is easy to dissassemble and you plumb it so you have lots of easy access to dissassemble and clean the unit. Also the parts of a UV system are fragile (glass tubes). Shop for a UV unit where the parts are very available, and even include in your purchase a spare tube, bulb and gasket collection.

To throw another wrench into the discussion, depending on what you are trying to accomplish with the UV, see if ozone is a better option. I am a huge believer in the use of ozone, and it is alot less maintenance.