I still say phosphates. I wouldn't add any live stock in fact I would remove it. Then I would get a power head and add hydrogen peroxide with massive circulation for about ten minutes or until the algae starts to brake down. (Can't really do that if you have lots of live stock or mosses.) Then do a massive water change and use phosphate remover to reduce the phosphates.
I actually intentionally grow hair algae for my cory fry they love it, or the bugs that live in it. Knowing how to grow it has increased my cory survival rate to about 85-90% of all hatched.
You could start breeding corydoras