if you're sure it's not the heat, it could be mite like Aqua said. Also, I hate to sound like a broken record, but coco is dry as hell. Thats not good. Your coco must be watered daily.
So I'm thinking you have root issues. With the coco going dry like that and when you come to water, may have made some anaerobic spots in the medium. Ph lockout is inevitable is you don't keep the coco saturated with fresh feed.
watering daily is not the same as properly watering daily. If you're not seeing water runoff the bottom when you feed, you're failing at coco and missing the point
At the risk of being repetative , i apologize in advance but....
Aim that fan horizontal , blowing warm dry air on the plant will cause issues , cufled leaf can be one of those issues...
The other plant is a different strain , and can be more tolerant / or more sensitive to different issues ,
check the EC of the runoff is my last bet to be honest. I don't think mites, because you seem to have your env clean and tidy. So I would check ec, that's all I got bud
Thanks fat cones I appreciate it man trying to figure it out just find it odd my other one isn’t doing it it still seems Heathy though just want to know if I need to be worried don’t wanna loose her