Rust spots on my purple kush!!! help!!!

Ok so the past couple days ive notice like a rust pattern of spots om alot of the leaves so i separated it and gave it a flush it looks healthy but those rust spots are getting worse now they turned into greyish patches and its slowly killing my baby!!!

growing in soil-fox farm ocean soil
nutriants-fox farm big bloom, grow big
1000 watt light
5 gal pots
good air flow
temp-70-80
hem- 25%-40%

Im attaching some pictures but there not very good but any advice would help please thanks!!!!!

might want to check for bugs on the underside of the plant

no bugs ive checked very good up and down the plant no bugs spider mites nothin....just rust spots and grey patches

i would go buy one of those testers they got at a hardware store that tell you if your nitrogen, potassium and ph levels are right

check Ph, if not that they might be a little close to the light

i'm having some small issues including a couple small rust-colored spots. after some research on this site and google it looks like it could be a mag deficiency. im thinking i might have locked my nutes up after going heavy on ph down then trying to adjust it back to normal. they say flush w/ some epsom salt mixed in to ph'ed h20 to correct this. im a beginner on my 1st grow, so i'm no xpert. i just read alot.

yeah checked my ph its like at 5 so i will go to the hydro store to see if boosting the ph will help