Brown spots on older leaves, turning to necrosis! HELP! (PICS + REP!)

Hi All,

I have a few plants in veg that are a couple weeks old, the older leaves on all of them have been developing brown spots(almost looks purple when it begins), and eventually starting to wilt away. Any ideas on what is causing it and how to fix it?

+Soil - ProMix with mixed with perlite
+Water - sediment / carbon filtered tap water (~150ppm out of tap)
+Nutes (currently taking around 520ppm - pH ~6.5-6.:
-Floranova Grow
-Heavy 16 Sweetner
-Sea Green Humic Acid
-Ful Power Fulvic Acid
+1kw MH light on 24/0
+Oscillating fan in room
+Light and room each have a dedicated fan to cool & scrub air
+Temps range from 68 - 74. Have dropped down to 66 a few times but not often.


Thanks for the help

Looks like a CalMag Fix

http://www.growweedeasy.com/marijuana-symptoms

Looks like it! I'll give CalMag a shot. Does it work better foliar or via soil for fixing this?


PS: Good link, bookmarked.

I do both, It has a low ppm ratio in my hydro set up. Be careful during flower, most will say not to spray during flower. and spray them while the lights are on. Don't soak the plants, mist them everyday till its fixed then every other day.
I use calmag in my res the whole grow.