First Grow Flowering discoloration

My problem: See pictures.

My setup: 6 plants, flowering at 12/12 for about 5 weeks under CFLs in a closet. I'm using Hydroplex plant food, hydroton, ebb/flow system.

My question: What causes this? What can be done?

Could be nutriburn. Not exactly too sure, but best of luck. I have one girl going on to her 5th week of flowering. Check her pictures out on my stuff and let me know. Keep me posted. Our babes are about the same age.