OK gents' I feel a bit late but bkg is a vamp daddy-o.. MG is a good soil to add as a filler. Great actually as a filler but I recommend adding a little bone meal, blood meal, lime, epsom, extra casting, a little kelp meal if you got it, compost, and I and I repeat I, water with a alfalfa meal, fossilized humate, and casting tea. But I sometime feel I might come off a little over the top.. but I've looked around I don't think I'm alone ( fdd, ohso, subcool, etc..) Oh ya and a must have guys and gals get you some clay heavy in silica add it to EVERYTHING!!!
Peace and Seeds to all..