I have cut most of the leaves that had BBA and my lights are on for 8hrs......but is continues to come back...So the snails wont eat this stuff..I have heard several people say that they will....I'd do away with the DIY CO2 and start cutting your lights. You'll want to manually remove as much BBA as possible first. Reducing the amount of time your lights are on everyday really helps get the stuff in check.
Lupin, I wish your nerites would teach my nerites to eat BBA! Mine won't touch the stuff. Probably tastes as gross as it looks.