Wouldn't use the Botanicare Cal/Mag (which is probably the 'Plus' right, with the EDTA in it?), you should mix dolomite lime into whatever mix you are using before transplanting in it. A heaping tablespoon per gallon of mix should prevent problems, both pH issues and Ca\Mg deficiencies.
How much of each of these things are you using, anyways. I know for a fact the Earth Juice Microblast has magnesium in it, even the molasses should have some Mg in it if it is Blackstrap (so that would be three sources of Magnesium). If you're using enough of each you really shouldn't be having issues.