Need help leaf curl

I have a few different strains and the only affected are my hinduXskunk the outsides of the leaves are curling up.I know its not the temp 79 and the light is 24in from the top.I did have a fan blowing on all the plants.I was thinking maybe they couldnt handle the fan??Im kinda stummped because its only that strain with the leaf curl.

same thing happened to me but it was an afghan strain - never figured it out and had a bad yield. i thought for a while it might be a pH issue, but it wasn't pH at all. i don't think i had a heat or humidity problem either. you might want to take a look at this thread: https://www.rollitup.org/marijuana-plant-problems/150004-plant-moisture-stress-symptoms-solutions.html

jeffchr said:

same thing happened to me but it was an afghan strain - never figured it out and had a bad yield. i thought for a while it might be a pH issue, but it wasn't pH at all. i don't think i had a heat or humidity problem either. you might want to take a look at this thread: https://www.rollitup.org/marijuana-plant-problems/150004-plant-moisture-stress-symptoms-solutions.html

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My plants have the exact same curl goin on.I know its not ph everything else looks great its just that strain