I will post a few pics as soon as possible, but until then, hopefully the community can help me out.
Bagseed. Foxfarm Oceans Mix. 1.5 Gallon pots. 6.4ish pH. BC nutes. 5 weeks. Temps under the MH can get between 80-90F.
I started some plants almost five weeks ago under a 125W CFL hood. They all sprouted nicely and started to outgrow the area I had them in, so I had to split them into two groups. One group stayed under the CFL hood and the other group moved under a 400W MH/HPS. Soon after I split the plants up, the group under the MH started drooping heavily and yellowing at the bottom. Meanwhile, the group under the CFL are still growing brilliantly.
Since my space is pretty confined, I had been planning on starting one group on 12/12 soon. When I saw this problem getting worse, this is what I decided to do.
I moved the "good" plants into the MH/HPS and switched bulbs. I took the "poor" plants and put them under the CFL to heal up and veg while I weed out the males in the flowering cycle. When I put them under the CFL, I trimmed all of the yellow/brown leaves and topped the plants. I figure that the plant shouldn't waste all of its energy healing a lost cause.
The only thing that I think may be causing this is high temperatures, but I'm not sure at all. The CFL area stays under 80, while the MH gets up to 90 or more at times. For ventilation, I have an 80 CFM above the MH/HPS and another 120 CFM blowing out exhaust from the top into a carbon filter/ionizer. Should I have more air blowing into the area? If so, what should I be doing?
I hope I have done the right thing. If there is anything else that I should be/could be doing. Please let me know. I'm trying not to panic, but I don't want to ruin my grow.