The Quikcrete stuff is *nasty* You'll spend hours and hours washing it, and it will STILL be nasty.
The "live sand" stuff in a bag is a complete crock. So it's got marine bacteria in it -- EVERYTHING has marine bacteria, including your empty tank. Skip it. You'll have more bacteria than in those bags in about an hour.
Look through Randy's old articles -- there's something about testing the sand with vinegar that tells you if i's aragonite or not. If the sand is aragonite, you are safe. The famous Southdown, for example, is aragonite sand; too bad we can't get it here.