This is right on. Coco and leds require cal mag and depending on you're type of lights 12" might be good or just slightly too close. Id say since they are not suoer dry/twisty on all leaves and not weird colors your light is fine. If anything maybe go to 16". Cal mag is needed so get on that too. I grow in coco and do 2 ml per gal every feeding day 1 i put my seed in to the last watering. Never get bad leaves. Could be heat in the tent, 75-80 is where i like to keep it or could be genetics as i know some strains do this such as real cuts of Glue twist leaves as well.I'd back your lights off a bit. 12 inches is pretty close. But idk anything about your specific light either. Are you feeding them with a Cal mag supplement?
Damn! I used to get that in my old tent. It went away when I built my room and got out of the tent. I suspect my tent had some light leaks.
Yeah, must be something with the environment here. IDK. Whenever I reveg, I get all sorts of weird stuff. Rainbow colored leaves. Odd shapes. I quit worrying about it. Maybe it's from the old nuclear plant, that they shut down around here??? LolDamn! I used to get that in my old tent. It went away when I built my room and got out of the tent. I suspect my tent had some light leaks.