Offhand (since I don't see a diary connected to this grow), I'd say you've maybe got two problems... first is overwatering (yellowing leaves midway up) and, perhaps as a result of that, some sort of fungus. The only other thing I can think of is a deficiency of either calcium or magnesium or both... I assume, since this is not your first grow, that you've checked the PH of your runoff... that should be between 6.0 and 6.5 with the "sweet spot" being 6.3 for a soil grow. But beyond that, I'm out of suggestions.... sorry!
Good luck!