Have a min? help diagnosing problem

Hi, everyone hope all is well.
Have a few girls in closet. (Rockwool cubes) Just saw my leaf is yellowing abit and leafs are crisp to the touch. Never had this before looks, like it going to the bud soon. Hope its not rot. Going to try flushing.
Any input would be great.

What temperatures have you got, how close is the light?
Looks like something like this....

thats been flowering for a while, auto i presume. they look over fed to me,

4 week,temp 80 ish, light 28 inch from plant. Got new pic. Not sure what wrong ppm is around 1280. Ph is 5.7

Thanks for your time.

You are running a little too hot on temps if not using CO2. Drop your ppm down until you can cool the room better.