Get ready to add new fish or plants to your aquarium with CaribSea Geo-Marine Florida Aquarium Crushed Coral. This substrate works to reduce your tank’s current bioload so you can add more finned friends or luscious plant life to your aquarium. The coarse coral offers plenty of surface area for beneficial bacteria to grow. It also works as a long-lasting buffer to help maintain water alkalinity. This substrate is great for tanks with undergravel filtration or elevated pH levels. It contains no ash, metals, pesticides or silica.