Well, instead of 12/12, you could try going with lights 11 on and 13 off.
To maximize your yield I try to do the following:
- Keep temps below 80 degrees. 76-79 is perfect.
- Keep day and nighttime differential temps at no more than 10 degrees.
- Humidity - 40-45%
- Give them the maximum amount of nutes they can tolerate without burning.
Good luck.