I spent a great deal of time and energy reading about sand substrate and the controversies behind it, and I wish now that I listened! I just came home from the Exotic Animal Vet and after $200+ the vet told me that my Leopard Gecko Leo had impacted sand inside of her, which is why she could not go to the bathroom, eat, move around normally, and she lost her vibrant colors. This can all easily be avoided by using paper towels or terrarium carpet. Unfortunately, the packaging of the T-Rex Bone Aid Sand Substrate read, "Beneficial to Eat" and I was under the impression that this would actually help my pet. I purchased my gecko and the substrate at the Syosset, NY PETCO where they told me this sand was the right thing to get for my gecko. My Exotic Animal Vet told me that she sees Leopard Geckos in her office frequently for the same problem, and warns against using the sand. BEWARE!!