UV sterilizer needed for reef tank

Hello all!

Thanks to everyone who responded to my request for references and links.
I've been reading everything I can find for the past two weeks, as well
as talking to other reef keepers in my area.

I run a UV sterilizer my 75g freshwater upfront, but that's because it
gets direct sunlight through much of the day from skylights and indirect
from the room's windows and tends to have algae outbreaks if I don't run
one 24/7. However, the 50g tank in my office has never (knock on wood)
had an algae outbreak and it doesn't have a sterilizer - but then
there's only flourescent room lighting in the office.

Half the people (and references) I've talked to say I need a UV
sterilizer on a reef setup (no matter what room it's in), the other half
say no. So, what's the deal? Do I need a sterilizer or not?

Thanks!

mark h