is this calcium def ? View attachment 2559553 or light burn ? light(600hps) is 2 foot from plant and tamps are ok.
Looks to me like your classic phosphorus deficiency,
on your next watering flush with distilled h20 and verify your ph with the watering run off method and a digital ph meter. An excess of fe or zn can cause a P deficiency.
Our lovely ladies love P its hard to give them to much phosphorus... other signs of deficiency is slow stunted growth.
Get your ph right if it isn't then add some P won't hurt.