This is the most popular soil substitute on the market. It holds moisture well, does not harbor pests and does not sour easily. This is enough for a 10 gallon fish tank about 1 inch deep. It can also be used for potted plants and terrariums. I use it in all of my spiderling vials , tarantula enclosures and roach enclosures. It is useful for regulating humidity because you can keep the coco as moist or dry as needed.