The Gravel Tidy with its unique design, is impervious to saltwater and will not rot or curl in use. Its perforations are large enough so as not to be blocked by sand, ensuring free flow of water. With the use of a Gravel Tidy it will keep coarser coral gravels and coral sand from intermixing, which destorys the appearance of the aquarium, as well as reducing the efficiency of the biological bed. The Gravel Tidy is the perfect method of separating substrate layers within the aquarium. This also allows plant roots to gain a firm grip on the Gravel Tidy avoiding accidental displacement tank maintenance.