BRAD,
ITS USED LIKE REGULAR SALT JUST MAKE SURE IT HAS NO POTASSIUM IN IT.
ALSO ROCK SALT IS VERY DIRTY AND WILL LEAVE SCUM
PARTICLES ON THE BOTTOM OF YOUR TANK. I HAVE USED IT BEFORE AND THE DISCUS SEEM FINE I JUST HATE ALL THE
CRAP THATS LEFT BEHIND.
HTH
CARY GLD!