Thanks for the suggestions man!
Yeah, salt build up is another potential issue... pretty sure pH is good, I have a Bluelabs pen that I calibrate regularly, and it's the only one of many plants getting the same mix showing the issue... I'm gonna give her a good flush, let her settle down and head to flower...
For everything else you suggested, I have no idea lol.... I'mma let you in on a little secret... I have no idea how to grow weed well, I just throw seeds at mediums and when I get bored I try different seeds and different mediums
To quote my wife last night... "no one else could grow weed like you. Your an idiot. Anyone else would kill these plants doing this"... I was trying to explain to her how to care for the plants and couldn't, cause I don't measure anything or pay attention to runoff, and at any given moment I have 3 different mediums going... also I'm prone to impulsively changing my mind and then insisting it was my plan all along...