So you're in 10 gallon pots and every time you feed them, they are each getting 2 gallons of water with 30ml of drench added in? That seems a bit on the heavy side for feeding to me, especially for a Haze cross. What run soil are you in? I just got done frying a group of plants in 3rd run thinking they weren't getting enough of the drenchs, when in actuality, it was the opposite.
Then again, bottom leaves turning yellow, normally means they are root bound, but I'm not sure if they react the same in bags. I know some people have had problems with the kit in grow bags, but others have done fine.
Also, it could be your RH depending on how low it gets. 50 is good, but where does it bottom out?
Personally, I'd cut the amount of drench your using in half, and see how they do. You are doing a plain watering between drenches, right?