Malkore is right...I should have been more clear about the sand. You definitely want aragonite based sand. Southdown and Yardright are aragonite sand...if you can find this, you'll notice it's marked "Tropical Play Sand". Most, if not all, other playsand is silica based. While you can use silica sand, it's not nearly as good as aragonite. I would buy the Carib Sea stuff if you can't fine the aragonite playsand.