I grow in coco, so I am quite use to watching for Cal/Mag deficiency and go through a fair amount of it. Soil is completely different and I think I only completed one soil grow ever, other than my veggie gardens and fruit trees which are all soil.
I don't ever use calmag in my anything soil related, but I do use epsom salt/molasses for additional magnesium and the other benefits. Especially for my peppers, they seem to love it.
