Aquarium Substrate Natural sand, without added colors or chemicals Creates a natural and attractive aquatic environment Excellent substrate for aquatic turtles Stimulates natural behavior Also suitable as a substrate for desert tanks Exo Terra Riverbed Sand is natural riverbed sand without added colors or chemicals. The sand is purified to remove impurities and achieve a uniform grain size. Riverbed Sand is ideal for many types of aquatic turtles as it is their preferred substrate in the wild. Softshell turtles, in particular, prefer the fine sand for digging and burrowing. Other aquatic and terrestrial reptiles, such as frogs and salamanders, will also benefit from Riverbed Sand due to its soft nature. Rough surfaces, like gravel, can easily injure skin tissues. Riverbed Sand is very soft and can be easily excreted when ingested, unlike gravel or small pebbles that may cause indigestion. Formed over time in an African river, Riverbed Sand is very soft and rounded, making it an ideal and safe substrate for the aquarium.