Sand works really well. PLEASE make sure when you do the last few rinses before putting it into tank, rinse it with TREATED water. (The stuff used to remove chlor. and heavy metals and all that). I think it helps get rid of anything harmful in the tapwater that might have built up in the sand during the rinse/washing. I add some to the last bucket rinse, stir it up good, and let it sit a couple minutes, and pour off the extra water. *Also, when siphoning up the fish poo every day, I only gently stir sand in 1/3 of tank, so the bio balance isn't messed up. (I saw this done on a youtube vid, when I was researching how to clean and maintain a sand substrate.) The only thing with sand is I have a hard time trying to grow any plants in it. So I have my plants in a fistfull of gravel. Hope this helps. Good Luck.