L@@KED EVERY WHERE!!! is it a Calcium or Magnesium Deficiency HELP!!!!

Profile:

1st time grow

Indoor
Super Skunk(Nirvana seeds)
Hydroponic (Bubbleponic/Aeroponic)
PH at 11:00 am 5.5 for both containers(I regularly keep it at 5.7 or 5.8 but, the nutes brought it down to 5.4 - 5.3)
PPM at 921
Rockwool and Hydroton Grow rocks
3rd week of veg (Seeds germination on Sept 02 2012)
I feed nutes for a 7 days
I water for 2 days (7 on 2 off)
LST and FIMMED

I just recent upped the nutes to 900 ppm(Previously 500) on the 1st and i woke up the next morning to notice the blemishing on one of my strongest plants
(I also notice a little shade of green on the roots but, the container i put them in is kinda clear white plastic so it could be algae or the nutes i used had a green tint to them too and it might have dyed them (Simple Path Nutrients)

The second plant is the weakest of all my plants and it suffered the same consequences but, the brown spots were from a previous deficiency so you can disregard that.
I have a 3rd plant that does not show ANY OF these deficiency which is located in the same bucket as my 2nd strongest plant (I not sure if it will or it might be that strong of a plant)

I just want to know what it is so i can fix the problems immediately. I was wondering if i should purchase a cal/mag product or should i buy cal and mag separate and depending on your responses?


Thanks in advance

PPP

It appears it's one or the other but either way, buy cal/mag and apply as they should be given together anyway.........

My plants had something similar, and it was cal/mag deficiency. The Cal/Mag liquid took care of the problem immediately.