Have you tried the peroxide treatment? When I had my algae outbreak from letting my CO2 run out, Rivercats suggested it. You pull of 3 cc of peroxide into a syringe and slowly squirt it over the algae. Do not do more than one syringe full every day or so. Treat each section once and that should take care of it. THe algae dies in a few days. Worked great for me.