You can't use play sand unless its aragonite based which most aren't. IMO you best bet is to just go to the fish store and buy some Caribasea brand sand. LS is not required but is nice if you can afford it.
Your sand turns into LS over time! It may not have the same stuff as the sommercial LS thats fromt he ocean (or so they say) but it'll have the same effect. I have CC and just placed LS on top...Makes a interesting Combo