All my tanks used to be barebottom, since I hate (!) gravel. I tried play sand once. My advice? RUN, don't walk, away from the play sand! It gets compacted and anaerobic within 2 days. I ended up stirring my sand 4x a day, and still ended up with black, nasty sand full of toxic gass bubbles!
Then, I found Petco sand. I'm switching all my tanks over to it: nice big grains, pretty colors, water ran clear with one rinse! (mine's black)
Pool filter sand would work, if you can find it. I couldn't, and it only comes in white. Also, has anyone had any issues with the pool filter sand being too sharp?