This is hydro, not soil, so ph should be 5.6-5.8.
As for the plant -- I've had both ph lockout and heat/light stress, and between the two, that looks like heat/light stress to me. Lockout starts to create deficiencies that can lead to damage over some time. Heat/Light stress crisps all the leaves like that overnight.
When it happened to me, my plants were about 5 weeks old. Once I corrected the situation (moved the light away another 6 inches), new growth came in very quickly and was perfectly healthy. The burned leaves stayed burned. Once I had two or three new nodes about the burned level, I pinched off some of the burned leaves, but then just decided to leave them alone. Looked horrible, but I figured the plant would let go of them if they weren't useful.