MEDIC! Yellow leaves and spots

2nd batch ever and my first batch died. 1000W HPS in a 4' X 4' room. I'm watering with a timer twice a day from a res with GH Florabloom, Floragrow and Floramicro. Airstones in the reservoire. They've been vegging for over 2 weeks. A spotty leaf developed and now most have a few leaves with spots. Also some leaves are light green. I change my res out weekly.

I'd never checked my PH till today. The tap is 7.6 and the reservoire right now is 6.3 (I filled the res with fresh nutes a week ago). How much could my PH fluctuate during a week with using these chems. Is PH my problem? What should I do to remedy this?

Thanks in advance

yup.ppppppppppppppphhhhhhhhhhh and some lock, burned up. get you ph to 5.8 with the hydro. lower ppm or ec to 850 or so.

Thank you so much. I followed your advice. I've kept my ph at no higher than 6. I've flushed and lowered the nutes significantly. 1 week later they looked much better. 2 weeks later they look healthy indeed!