SUDO Reef Sand SUDO Reef Sand is a natural clean sea sand. Reproduce a landscape that is close to the natural sea condition. This bottom sand is exclusively for saltwater fish. SUDO Reef Sand is an all-natural, pre-washed sand that does not alter water parameters. Benefits For saltwater aquarium Mimics natural ecological condition for fishes Clean sand, free of chemicals - safe for fishes and plants No maintenance required unlike gravel substrates