PREIS Dark Caribic Sand is a pure rock material with a high percentage of calcium and magnesium. The dark beaches of northern Martinique are especially mystical and fascinating. Thanks to the PREIS Dark Caribic Sand, the colors of the corals and fish become even more brilliant to the eye. Vibrant colors are more fluorescent and terrifying gobies or wrasse feel more confortable here than in the typical bright, white sand. We recommend a depth of 2-3 cm for aquariums.After approx. 1 year, one should refill the aquarium with additional 10% PREIS Dark Caribic Sand as this is the amount that dissolves. Invertebrates, like anemones, feather duster worms, sand snails, digging starfish, and wrasse like to bury themselves in this fine, PREIS Dark Caribic Sand. Gobies and pistol shrimp can chew through this sand easily and dig caves.