Grand daddy purps

First time running this strain but I have smoked plenty .just curious on others experience with ppm and ph in coco ? How’s the stretch and train ability? Scrog
Usually in the past ran ph at 5.8 allowing drift both ways . Start at 200 ppm and ramp up to around 900
I’ve heard the old grand daddy likes it a bit dryer humidity ? Can wait to get this strain in a bowl .

We’re limited to 8 ft ceilings