leaves yellowing and spotting

soil- roots organic potting soil (straight out of the bag)
pH- 6.5 soil pH measured from runoff
Nutrients- General Hydroponics GO box fed once a week
last watering 5 days ago with pH'd water only (using pH down from GH)
pot is 7 gallon smart pot
light is 150W HPS
temp range between 69 and 74 F
humidity is between 40 and 50%
plant was FIMmed about a week ago no other pruning
i have checked the N level with the rapid test kit and it fell right around the sufficient reading
other than testing over the last few days and normal watering the plant is left undisturbed in a box with adequate air circulation provided by a fan and co2 is provided by a co2 bag
the plant seems to be getting worse over the last few days and i am at a loss as to what it could be. the light is roughly 18 inches above the top of the plant and this is the only plant i am growing so nothing to compare it against.

I've used the GH Organic Grow box before. Are you using all of the nutes? At the recommended rate or other?
She really looks like she has a Calcium and probably Magnesium deficiency.
But overall she looks rather sad. What is your CO2/ventilation schedule and what ppm?

my co2 is the exhale co2 bag its in the box at all times and the air ventilation is running at a rate to completely replenish all air in the box multiple times per minute. its a can fan hooked onto a can fan filter. i dont have a TDS meter but will order one so i can get to the root of all this. I am using the week three veg recipe on the box at exact amounts and i am including the bio marine each time

Some Epsom salts will fix it fast and cheap.

just ordered a ppm meter so will report on that soon and epsom salts are definitely something i can do

do you have a good number for the amount of epsom salt to add. ill put it in next watering.

Im very rough on this one so you may want to do a search. I use 2 to 3 teaspoons dissolved in a glass of water and just poured on top. This days i just wack a very small hand full in with my soil mix when potting up. (i grow in soil) and problem solved before it can happen.
Its close to impossible to add to much mag. (dont try to prove me wrong...lol)

thanks for the help guys.

@MoistBeaver make sure you are not dealing with a copper deficiency dude! Shiney leaves, problems all over the plant!

Magnesium is mobile so it usually steals from the lower leaves first until they fall off completely to feed the tops. Your problem looks like it is from top to bottom.
Copper deficiency can be across more of the plant, will leave a shiny appearance on leaves and you get that darkening of the inner part of the leaf while yellowing of the tips working inward.

Cannabis Copper Deficiency Symptoms

• Leaves turn dark with blue or purple undertones
• Tips and edges of leaves turn bright yellow or white
• Shiny or metallic sheen on leaves
• Leaves may feel stiff and start turning under
• Tends to affect leaves directly under the light

I'm not going to say it coudnt be magnesium, but the pictures of your plant do seem too evenly affected.

does anyone know of a good test to see if my copper levels are low. nothing good came up on google