Fan leaves dying and spreading up plants

I have 2 plants that are little over a month old. The fan leaves have been dying off and making its way up the plants. The leaves start dying from the tips then get soft, yellow, crusty, and brown. I may be over fertilizing or a ph problem? Should I flush my soil?

its heatstress and id also check the PH.

Ive check my ph. Its around 7.0, I have one of those ph meters that changes color in the water. Kinda fishy but it works. What could I do about this heat stress? Move my lights around? Ive got a fan circulating air.

post some pics.

ok leat me take a few