purple fan leaf stems/yellowing with brown spots

I'm growing some Purple Kush. im keeping my mothers (1 at the moment and 2 as soon as i can cut myself another or buy a different strain) in a 2x3x4 plywood cab with 100cfm of pc fans for ventilation under a 150w HPS running at 18/6.. i plan on taking 10 cuttings(4-6") every 2 weeks. im just using fox farm ocean forest for soil with 40% perlite and fox farm grow big for nutes.. Its not doing extremely well at this point.. the fan leaf stems are purple with yellowing on most of those leaves and brown spotting.. older leaves are dying if not already dead and plucked.. not too sure what this could be.. im using about a teaspoon per gal with arrowhead water. ph is 5.6 going in and ppm about 575. it has been a little hot in my cab lately, up to 85.8* at canopy level.. but now that problem has been fixed.

I won't be able to post picks til Monday, but I was hoping somebody knew what this was.

Thanks for any advice!

so, i think its probably a ph problem,, i've been feeding my plant with 5.6ph water... should probably turn it up to 6.5 for soil im guessing... whoops.

do you guys think thats what the problem is.? or could it just part of it?

looks like nute burn and i think the purple is genetics ur growing purple kush so there gonna turn purple

Yeah, that looks like over feeding. Though it could be nute burn.

Classic nutrient burn, flush it!
You cant forget that the 500-600ppm range is for no other nutes (including soil!)
drop the ppm down to 500 or less & see whatcha get