Root rot?

Hey y’all,
This new grow has been a straight nightmare, electric problems, heater failed, ph pen broke and now plant problems. Definitely could be a ph problem but just trying to rule things out. They are grown in coco Perl, gen hydroponics full line and recharge. I know that recharge can “stain” roots as Scotty says but I’ve never seen this before. And yes I cut holes in the bottom of the cups. Lol

In my experience, roots rot because they are constantly wet. The bigger question here tho, is why aren't you up potting?