Leaf Curl??

Can anyone tell me what this leaf curl is from? I just fimmed the plants 3 days ago but I have been seeing this curl for about a week or two on the big fan leaves. Posssible heat problem from the lights being to close or not enough water or too much? The bottom fan leaves are fine
I have been using Hesi Nutes for earth, I was also spraying the foliage with Hesi Super Vit.. Take a look and shoot me your ideas or suggestions. Thanks

i had that problem also, I would raised my T5's to 12" keep an eye on them still and look if ur leafs are turning yellow if they do is nute burn, but nute burn doesnt always curl up the leaves.

I too have this problem, but only with 1 strain - Lemonhaze. I posted in this forum looking for advice too. What strain is yours?

It is caused by heat stress and high temps - now if the leaves curles down and look like a claw it would be caused by Nitrogen toxicity ("N") What type of lighting are you using?

Delicous seeds critical sensi star..samura seeds el aquamista. I am using 6 Cfls.. 4 32w 65k and 2 18w 27k. I plan to start flower next week just ordered 250w hps that I plan to put in a cool tube