green water

hello everybody,
I have a 30 galon salt water aquarium, my problem is green water . It started with green algae on the sand, one day I added fresh water because the salinity was too high, next day water was green and algae from sand was gone.
now I heard that UV Sterilizers will kill algae in water, I found one that is called "Laguna power clean 4500" paid $10 at a spca thrifty store. it seems to be working(I can see light works ). however this is for a fresh water pond, up to 1000 galons.
Priovided I do all the apropiate conecctions to a pump (small for this tank) , will this be ok on my tank?
is there any differences between UV Sterilizers for salt or fresh water?
thanks.
rick

 

I think a uv light is a uv light as long as you can hook it up should work I would think

 

Running some carbon will help with the water too.

 

protein skimmer if you don't have one get a good one

 

make sure none of the plumbing in the UV unit is copper. $10 is a great price.

 

thank you guys for all your replies, I will try to hook it up to the tank.
yes it was really cheap, the old little lady at the counter did not know what it was, so she said "just give me $10." the box still had the sticker from the store $179 canadians. It had been used allready though.
rick

 

just to update you guys, the uv sterilizer is working, I hooked it up sunday night and by wednesday is allready getting better,this green water problen I had it for allmost 3 weeks, it was so thick that before I could not see farther than 4 inches , now I can almost see all the way across the tank.
besides the uv light I also covered the tank and kept the lights off, turned them on just to feed the fish.
rick

 

lighting!!!! i don't have a timer on my fw or sw tank so i make sure to regulate my lighting manually water changes and less lights is the quickest way to clear things up....oh yeah and replacing filter media

 

One usual question that no one has asked yet, the straight water you added to reduce the salinity, what was its source? Tap, RO/DI, etc?

 

it was tap water, I know it contain algae spores. how do I change water and not worry about spores?
thanks
rick