Man, i think you saved my life, i mean theirs.
I followed the link you posted and surely the plants are being over watered. Twice a day it's too much, even under the 400w light and using low amounts each time. I'll do it well once every 2 or 3 days.
Now they're not being feed for 1 1/2 days and seem alright.
Hope that's it, combined with the high temperatures. Now i took 10 degrees off. It will work