It seems I'm starting to have this issue too. Yesterday, it was only one leaf curled under but today there's a couple more curling under and it all started after I changed my reservoir water. All my plants share the same water/nutes but only one plant is exhibiting this behavior, so if it was nute related you'd think all my plants would have curling leaves
right? Not to mention the one plant that is having issues is the biggest/tallest by a long shot (you'd think the biggest/tallest would be able to handle the most nutes of any). My room fluctuates between 66-80F so it's probably not temp related, although since it is the tallest plant, it does sit pretty close to the light but my hand passes the "burn" test (it doesn't feel hot). Water PH is about 6.0. Highpsi mentioned that increasing the nute strength too quickly could cause it too, and that is definitely a possibility (The res was filled with water + nutes 3 weeks ago and I did not add any additional nutes when I occasionally had to refill the res). The watering schedule is shared amongst all my plants and has been the same since day one (one min on, 5 mins off - aeroponic system) so it's probably not over/under watering. I've never heard of EC nor do I have a ppm meter so I can't give numbers on those. My ladies are on their 4th week of flowering btw.
What do you guys think about this? Will my plant still produce big buds with curled leaves?