Getting the right substrate for the bottom of your turtle tank is extremely important for the health and well being of your turtle. Regular Aquarium gravel is NOT suitable for turtle tanks and can kill your turtle if swallowed. We recommend the use of fine sands in conjunction with some Calgrit for the base of your tank. All of the sands below are suitable for use with turtles. If you currently have gravel in your tank we highly recommend that you remove and replace it as soon as possible.