Anyone have a few minutes to help out a hydroponic noob?

I started out using 6.5 PH water. After nearly killing my poor girls the helpful lads at the hydroponics store in my area told me Soil and Hydro don't use the same PH, imagine that.
Anyhow, they were off to a rough start. With some careful 5.7 PH watering and flushes they really started to take off, now I feel as if I am starting to see the growth slow down and they are showing a few signs of damage. Please help if you have some experience in hydroponics.
https://www.rollitup.org/blogs/blog25244-help.html

Def keep your ph at 5.6-5.8.

Is the damage on new growth or old growth? Some of that damage may be residual from the lockout that might have occurred when running the higher ph level. If new growth is good, then just let the crispy stuff grow out.

How old are they? Are your ppms still at 600?

And what's the lighting situation? What are you using and how far away are they? Some of that curling/crisping could be from light stress.

i see heat and to much nute issues.