Thank you Mr. Krip!
I ended up reducing the lights down to 3-bulb after they had about 9 hours of darkness. I've been on a routine of every 5 days to give them 8-12 hours of darkness to rest. Today just happened to be a 5th day which was fortuitous.
They bursted with new growth from that little rest and have recovered well, but then again, I just turned on the lights again.
About the nute burn. I have them in roots organics soil from the very beginning with coco mixed in. I've only given them EWC and Guano as top dress once last week. Then the waterings have been with SuperThrive and Pro Tekt. pH is steady between 6.5 - 7. Do you think those 4 items could cause that type of burn? I guess the top dress takes time to settle so that is why?
Leaving in a week for 5 days so I'm VERY VERY worried about time away from the babies. A friend told me "a good farmer never leaves the farm until after the harvest."
I'm a bad farmer! lol
My guess is the Bat Guano was the culprit. It can burn young plants depending on the quantity applied, size of the plant, etc.
Here's a good old post on using Bat Guano:
Bat Guano for Organic Indoor Gardening w/RooRman