From my reading and understanding, "Play" sand is sterilized, and by law should not have any silicates do to the fact they should not be inhaled, let alone by a child at play.
Do some more reading, and always do the "Vinegar Test" this shows the sand is calcium carbonate based. Among other things. Most all the guys here on RC who setup DSB or huge systems with sand use Southdown.
I also use Randy Holmes-Farley's 3-part Calcium / Alk / Mg supplement, that uses Epsom Salts, Calcium Chloride (Dow Flake / Ice Melt), and Baking Soda! So, all I can say is read up, learn to save your money.
