New growth turning highlighter yellow. Help needed

So I'm about 40 days into my first real solo grow and so far things have been pretty ok... Except for a little concern on losing color (just needed some feeding) things were good till yesterday when I realized the sleeskunk plant has bright yellow tips like a highlighter (pics attached). Right now I have 4 plants , 3 sleeskunk reg and 1 ak48 fem under a mars hydro 300 and an hlg65, they are roughly 15 inches from the tops..I just transplanted last week from ffof into ff coco loco and have since been feeding the 1/2 strength ff grow big and big bloom. I tested my soil ph and the run off was 5.77 too low? Any help would be much appreciated. Thanks family!

I do not think its a nitrogen def cause that usually effects the bottom leaves first and the entire leaf tends to turn yellow.
Yeah the run off is a bit low 6.0 -6.5 is ideal however with 6.5 it can cause an iron lockout I believe (read that some where never experienced that tho).
Hope this helps.

Maybe a little nute burn and lockout bro! After your transplant you should have fed plain ph water for a few weeks before re introducing nutes dude!!