Forget the red line. The only way for that to be positive is to get people to fold before the river. That's not going to happen in 2nl, 5nl, 10nl, 50nl, whatever. I'd hazard a guess that a lot of people have a negative red line. I do and I'm not worried about it. The only line that matters is the green line, really.

Don't get hung up on stats. I'd suggest you play less tables because I don't think you can learn much playing that many tables. You've got to overcome your propensity to play poor hands because you get bored. Try 4 tabling 6-max. You can play more hands and it's faster so less boring.