I used the silica all purpose mix from Menards. It's white, finer than sugar, and was like $4.50 for 100lbs. Otherwise, if you can find the all-mighty yet elusive "Southdown" sand from Home Depot, that's what seems to be prefered, but I think you have a better chance of convincing Bush to pass an environment friendly act then finding it. Basically, buy enough for 4" in your tank, then buy a few pounds of the live stuff, and kind've put it in various areas around your tank, as the top layer. This should get things rolling.