Southdown (aka. YardRight) sand is available only in some parts of eastern Canada but not in the west. Calgary for sure doesn't have it and some people use sandbox playsand which is supposed to be free of silicates. (makes it safe for children)
You can also buy sand from your local specialty garden supply centre if you can't find the right color. They may contain silicates but whether this will affect your fish or not is for you to decide. (This is one of those myths that is along the lines of "microbubbles"
)
Depending on the size of your refugium, just bite the bullet and buy a bag of Carib-Sea aragonite. Just put the "good sand" is the refugium and use the cheap stuff for the main tank.