Well, find the root of the problem, but to help you get a jump start, as long as you don't have any real aggressive fish, go get some mollies from the lfs, Petco has them cheapest and for freshwater fish it doesn't really matter. They are about a buck a piece. I had the same problem as you, well, hair algae and caulepra algae were taking over my tank. I tried everything, and no matter what i did i couldn't get it to stop, water changes, a tang, phosphate remover. Everything. so i took one of my mollies out of our FW tank and dripped him for 4 hours to get the salinity to match. A week later, no more hair algae, and very little amount of caulepra left. She is still in there today along with a mail and not only to they keep algae growth down, about every two weeks they spawn live babies that they're tank mates love to eat.
Another option for hair algae is the lettuce nudibranch. But i have no experience with them, try a search on RC for them and you will find tons of info about experiences with them.
thats all,
good luck
Austin