Aqua One Gravels are safe for use in aquariums. This range of Australian -sourced natural gravels are non-toxic, as well as being completely inert, so they will not dynamically alter the pH of your water. They will also assist in the mechanical and biological filtration processes, and can be used as a substrate in fish and shrimp tanks. Available in a range of different natural shades to help you re-create a natural look, there is one to suit every aquarium.