I would cut the lights off completely for a week or so. I had green scum algae out the wazoo in my 75g tank. I figured out that the problem was I was not dosing any ferts at all and my co2 wasn't turned up high enough.
In order to get rid of the green scum in the first place I turned off the lights for a week and left the tank blacked out. It worked for me.
In order to get rid of the green scum in the first place I turned off the lights for a week and left the tank blacked out. It worked for me.