If you rinse it a lot,then rinse it some more,then rinse it again,then bake it,it would probably be fine.
Having sand in a planted tank is also fine.
But considering pool sand and play sand are so cheap,do you really want to risk it in a tank with a few hundred dollars worth of discus?
Having sand in a planted tank is also fine.
But considering pool sand and play sand are so cheap,do you really want to risk it in a tank with a few hundred dollars worth of discus?