Leaves spiraling and cupping

some of the leaves on my white fires are turning sideways and starting to cup down and fold up, i want to know whether this problem is due to heat stress or the fan being to strong before i try to fix one of them.

looks like ph prob.. twisty leaves and what appears to be mg def/lockout

i agree with ph but also the downward clawing and burnt tips are saying nute burn also.

What kind of Burn do you think, They've been having a potassium deficiency so that very much surprises me.