I am setting up a fw ray tank its 300 gallons and I am trying to figureout what sand to use? I can either use Playground sand, Quikrete medium sand, or pool filter sand. I want something that wont hurt the disk of the rays and also something that wont cloud the tank every time the rays move. I have lots of experiance in SW but this is my first FW tank. Please let me know what you think...Thanks