Personally, I would love it if it could kill the plantonkic stages of bristleworms. Doesn't seem to. I have too many. Also I've seen no impact on my pod population. Even my Mandarin and 2 wrasses can't make an impact on them. Actually, my pod population has increased. I think this is due to more macroalgaes for them to hide in. Luckily, I don't have any animals or corals that need phytoplankton or whatever is being killed off by UV though I have read that the amount of phytoplankton in the tank is insignificant as a food source.
I have to say that I had no idea what was going to happen to my tank when I was installing the UV. After having seen the results, I am far too happy.
Just one of many articles:
http://www.aquariumadvice.com/articl...q=2&fldAuto=31