First off, how old is the water in your pool? I had the same thing last year and had forgotten that you really need (at least in my area, Arizona) we need to change out the water every 5-6 years.

Drained the pool then did an acid and chlorine wash on the pool and it looked like new. Before that had wasted loads of $$ on chemicals trying to get the algae gone and it just did not work until we changed the water...