I'm currently growing in mg "hempy buckets" I use equal parts mg to perlite and water daily.. up until about a year ago I was an outdoor grower and still used mg, no pots just planted right in the ground after germ.. both cases I use mg bloom booster, their flowering nutes are actually designed to be ran hydroponically or exclusively through foliar feeding. Because of this only their flowering nutes don't have a soil penetrant ( I don't know what that is, but it sounds bad to me) they also have more chelated ingredients......their dirt does not contain micro nutes only npk values....I use AV mg and the equal parts perlite to add drainage and to cut the nutes in the AV ( straight AV can burn seedlings) but AV has more peat and coco, I've tried all their soils and even though this has a bit more n the medium is perfect. I absolutely hate the seed starting mix, in contrast its like a powder. When dry if you blow on it, its like a smoke bomb. Just my experiences....
Anyway mg bloom booster has boron copper iron manganese mo and zinc. Its missing the really minor nutes, silicone for example but it does have everything you need to grow healthy plants besides calmag