Would this substrate be fine for Stingrays? I couldnt find any information on whether or not it has Silica. Can anyone fill me in? http://www.petco.com/product/112365...bazaarvoice-_-RLP-_-112365-_-productname_link Also, if I were to get this sand, how would I calculate to fill my tank with 1 inch thick layer of sand? Thanks!