In all my thread reading this last month there sure are a lot of people having these problems with floranova in coco. Just saying. I sure would never use that stuff in coco.
Your pH is probably too low preventing the Mg from being absorbed by the plants, most commercial ferts have sufficient amounts of Mg, and since you are adding Calmag also, there should be plenty.
Calibrate your pH meter, water with pH 7 water with no nutes added and check the pH and EC/PPM of your runoff. I suspect you are below 5.7 or so, which is causing he lockout. If so flush your system with high pH water (8-9) for an hour or so then reset your pH in the reservoir to 6.3-6.8 and the plants should bounce back within a couple of days.
Hope that helps,
-Chimera
Did you collect your runoff yet as suggested above and take the pH / EC? We can't help you without your cooperation.
I've seen your plants and you haven't got a magnesium deficiency.
You've got some problem, but it's definitely not a magnesium deficiency and it won't be solved by adding more or trying to make it more available.
NOW we're getting somewhere. if you would've only divulged this info sooner...Actually today is actually plain water day. This is when I use just a regular water with no food or any adds. I just ph it to 5.9-6.0 and flash them.
I feed 4 times every other day and then plain water flash.
Here is what i found after a week of searching and talking to various people at various places All though CalMag has N in it, as a nutrient it is still very beneficial to plants at any stage. I decided not to cut it out of my regiment completley. I continue to use it as recommended.