Dumb question, I know. I recently purchased a new tank, a 50 gal acrylic, and i am in the process of moving everything from my old 20. i need MORE substrate to form a dsb, and when i wnt to yardright.com, which used to be Southdown, it says that their tropical play sand is not safe for aquarium use? Why not? I have heard that it compacts down too much.
http://www.yardright.com/sand.htm#playsand
http://www.yardright.com/sand.htm#playsand