Mg is just a brand name for a plant food just make sure to
get the correct N-P-K level for your stage of growth and
use at 1/4 strength. Actually MG contains magnesium and
sulfur so you wouldnt have to add epsom salt to the solutoin
to make up for those missing trace elements that a lot of other
plant foods do not have.

Mg soils are what you want to avoid.