Any cal/mag will do but i still wouldnt like to guess what it is, i know of sensi cal/mg for bloom, 3:1 cal to mag ratio, should be pretty good.
As for the biobizz, yer it can burn but i find it very hard to even feeding most waterings, i know the whole organics debate is wide open and i now subscribe to natural over simply just pure organics but i can see why people love biobizz, it is so forgiving, gives top results and apart from lacking enough cal/mag i really really like it a lot, probably be hard to ever change.
On a side not my plants are mag whores, i thought 25ppm mag to 80pm cal would be enough but i am still left with mag deficiency on my plants, sucks having a small mag deficiency when everything else is right, the ones that had an extra feed of epsom salts a week or two back are now bright shiny healthy green, the others are a lot duller, suppose i am lucky though just knowing my mag needs upping for perfect results. Peace