Great solution to the problem with NFT: for nutrient to flow over the roots, you've got to have more roots down where the nutrient solution flows!!! A temporary flood/drain conversion was GREAT problem solving.

Your calmag hunch was correct but that looked more like a calcium deficiency.

Green light... wierd, I assumed it was your 'stealth night work light'... plants can't see green, so you can go bother them while they are sleeping by using green light. I hope it's your camera, because the only HID that puts out really green light is mercury vapor, and that is not useful for growing.