Dry Aragonite Substrates – CaribSea s dry marine substrates are recognized worldwide for their purity and precision. Our substrates are purposely engineered and free of impurities such as ash, metals, pesticides, and silica; which allows you to create a safe and beautiful environment for your fish and invertebrates. Precision grading makes system design a breeze! No matter what type of system you are setting up, we have the substrate that s perfect for the filtration method and habitat you are creating.