Is this heat stress of nutrient related (pics)?

Plants are in 100% coco medium and are fed with Canna Coco A+B. I have not used any supplements yet so I think there may be a deficiency (magnesium?). Or could it be heat? It's only a 400watt light about a foot away. My hand only gets warm under it, so I doubt it heat, but I could be wrong.

What are your temps? Can you describe your air intake and exhaust? etc...

Looks like my plant when it grew too close to the light.

Temp is usually around 79 but it has reached 86. There is good airflow over the tops of the plants, and there is younger and more fragile leafs that were closer to the light that did not burn...

That is a good example of heat stress but there is a small chance that you might have a problem with your ph but unlikely.

PH is around 5.8, so I guess it is heat... So no one thinks its a deficiency? I would think that the tender foliage closer to the light would burn first...

I'm thinking ph or nutes maybe da issue cause
of the major drooping and curling under with
uneven color this is the dark and light green on
da leaves with brown edges~

I don't think it's the light, you do have a fan blow on them?

yeah Ph My last plants did the same thing as well as the one i have now it is starting in my last plant growing ing coco soil mix i kept the ph at 5.9-6.4 and everything worked itself out way before 12/12 was induced but the plant i have now is in pure coco and i am see slight sign of this so im going to try to get ph in right range being that i am growing in pure coco im thinking ph is going to have to be lower than previous grows but i will find out and give updates as this plant comes along.

this is not heat stress imo, the leaves would first curl upward on the edges. i think its either hot soil or ph imbalance.

ok so the edges did curl a bit. I still think its ph or nute burn.

I am almost positive its not heat related now. The lights have been backed off and the temps are way down, but the problem seems to be progressing. I assume since its coco the PH is prob too high, although I am watering with PH adjusted water at around 5.8. People tell me not to measure the PH of the run off but I do anyway and it is always kinda high, around 6.8. Should the water be lower than 5.8 PH, or maybe they just need a good flush?