Magnesium Chloride?
 

Anyone know of some bulk suppliers in Calgary area?

you mean more bulk than what we have at the store?

from here

Yeah more bulk than at RC. I'm looking for a 5 gal pale of it at least. I've a dire magnesium deficiency.

I'd have to look up the name
 

There is a raw chemical supplier in calgary, Univar I think. I bought a 25kg bad of mag chloride from them (about half the cost was shipping). I think it worked out at around $1-2 per kg or so. If I remember Calgary and Winnipeg are where they actually warehouse it, as I couldn't get it from Vancouver.
I don't remember the cost breakdown, but I'm sure the mag was under $1 per kg without shipping.