This question probably belongs in the general hardware forum. That way both salties and freshies can weigh in. A moderator will probably move it.
Ok, so you are having algea problems...
Its hard not to get into specifics with algea because there are so many things that cause it, but i will just say this...
I bought a UV
sterilizer for my saltwater tank, and it has not stopped the spread of algea on live rock, but it has slowed it down. UV
sterilizers are better for green water algea than any other in freshwater tanks.
That particualr sterilizer can onoly be used with a HOB
filter. You need a canister filter whhere it can be attached inline.
They are expensive, but there are better ways of dealing with algea. It takes work, no real easy way out.