New Sealed Room - Now Showing Deficiencies

HI Everyone!!  Thanks for having a look at my issue.
 
We decided to expand our mother and clone rooms, and since we were expanding, we thought we would go ahead and seal the rooms in order to better control the environment.
 
The rooms are basically 15' x 15' with 10' ceilings, so a pretty good size and plenty of room for expansion as well.  Both rooms are pretty much set up the same, with the same Equipment.
 
1.  We wrapped the room in Panda Film.
2.  Installed Air Cooled lights and Vented those in a closed loop so the room is not vented, just the lights.
3.  Installed a CO2 Burner Hooked up to a large Propane Tank along with the Atlas 8 Controller.
4.  Installed Mini-Split Air Conditioner/Heater.
5.  Lots of Oscillating Fans blowing air all over the place.
 
The rooms are not TOTALLY SEALED as there are some Nooks and Crannies such as Electrical Outlets and some Door gaps, but these dont seem to affect anything.
 
Both rooms are kept in the 78 to 81 degree range with humidity sitting between 60 and 70
 
CO2 in both rooms are set to 350ppm.  Since we are not flowering these plants, we only need the CO2 kept in the Normal Range.
 
So everything seems quite nice, but for some reason now the Plants are showing MAJOR Magnesium Deficiency.  
 
We are using COCO, so of course CalMag is not unheard of, but didn't need it in our last Open Vent Grow room under T-5's.  Now I am adding the CalMag to my feedings, but not sure its helping any.
 
Anyway, all of a sudden the plants are demanding Higher and Higher Nutrient PPM's,, and I wanted to see if this is a common occurrence?  The new Growth is Nice and Healthy, but the lower leaves are showing Magnesium Deficiency BIG TIME!!  I realize the introduction of CO2 would stimulate the plants a bit, but its not like we are running 1200ppm,,,  Without the Burner running in the Clone room, it stays in the 500ppm range and never falls low enough to trigger the Burner, so I have a hard time believing its a Propane Burner By Product buildup causing any issues.  The Burner in the Mother room only comes on about 4-5 times a day, and that is only for a few seconds when it Kicks off at 400ppm, and climbs to about 500ppm, where it spends the next 3 or 4 hours slowly coming back down.  We do go into the rooms a few times a day in order to check on everyone, water, etc,,  so I would imagine we are also getting some fairly decent exchanges.
 
I continue to throw more Nute PPM's at them but cant seem to catch up to the Deficiency.  I went from topping out at 800ppm (.5 factor) in the last room to 1200ppms now, and still not sure I am catching up to it.
 
In fact I have seedlings that Sprouted on July 1st that I am now up to 1000ppm, and it looks like I will have to continue climbing in order to get the whole plant healthy, not just the Tops.  I have been growing for some years now, and would never even come close to these PPMs without Burning the Crap out of the girls, so this is all New and Odd to me.
 
Anyone with Some or Same experience, that can chime in on this for me?

 

I was using CNS17 for Coco / Soil, but they recently changed and combined both the Hydro and the Coco into one.  Yes of course they made this change right as I moved the girls into the new rooms, but I have to say, I dont think that's the problem, cause I went ahead and added the CalMag.
 
Yes, I am getting good runoff, but even the Younger (not even a month old) plants that are in Coco Solo Cups are having the same issue, and I know those cant have salt build up already.
 
The HID Lights are only 400 watts (x's 6), and of course I figured that slight upgrade would require a little bit more nutes, but the Clone room is still using one of the T-5 (8 lamp) 4' florescents that I am using to Cup Seedlings and Clones, so those are still under the same Florescents as before.  No HID's in the Clone Room, just the Mother Room.  Oh and I must say, the clones have never looked so good.
 
The whole thing is just ODD,,  The SLIGHTLY increased CO2 has just shot the Nute PPM's through the roof, and I am having the hardest time keeping up with it. 
 
My concerns have been Oxygen Depletion for the Dark Period, but not sure how to confirm this one,,  Or gas build up from the plants that is not being vented enough.