The aquarium substrate has important tasks for the water chemistry and the well-being of the aquarium animals. Calcareous materials buffer the pH value and ensure more stable water conditions. The substrate is a separate biotope for a variety of very different bacteria and animals such as crabs, snails and worms. Many fish also need the substrate to feed on the animals in between or to dig in at night.
Only use lime-containing materials for the substrate in seawater aquariums. Under no circumstances may quartz sand or similar materials be used.