One of the exciting parts of working with "botanical-style" brackish aquariums is the idea of creating a more "functional" environment in our aquariums. And it starts, literally, at the bottom. The soft substrate in which mangroves grow creates habitat for various infaunal and epifaunal species, while the space between roots provides shelter and food for motile fauna such as prawns, crabs and fishes. We are big fans of utilizing multiple materials to create a diverse, multiple-particle-sized substrate. A substrate composed of a variety of materials will provide many of the "functional" and aesthetic elements of the natural brackish water mangrove habitat. Brightwell Aquatics "KoraLagoon Substrat" is an excellent material with which to help construct such a substrate. It provides the ideal combination of particle size, composition, and aesthetics to provide a great supplement to a diversified brackish water aquariums substrate to support natural biological processes. While this product is aragonite-based and was created primarily for reef aquariums, providing buffering, trace elements, and various particle sizes to support micro and macro fauna, we've found that it provides many of these same benefits for our brackish water aquariums. We highly recommend using this in combination with other substrate materials to create optimum conditions in your brackish system!