Anybody got any idea with what's going on wit...

Nutrient deficiency, namely potassium. I know GHE recommends to cut the Gro formula and that the micro and bloom should cover it, but I've had to add it back in a couple times when early signs of these symptoms occur. It actually makes sense that the runt isn't showing these signs, imo. She's smaller, not eating as much or has the same nutrient needs as her bigger sisters. So she's in her sweet spot, but the others need a small K adjustment👍. Recommend using 2ml of gro, per gallon for the feed. This question is somewhat old so I don't know if you've started the flush already. If you have, I wouldn't worry about it as they're wrapping up anyways. Hope this helped and happy chop my friend. Cheers.👌