Gravel is an important part of every aquarium, and Aqua Culture Aquarium Gravel in Black will keep your aquarium healthy when you add it to the bottom. It not only beautifies your underwater world but provides a surface for the growth of beneficial bacteria which help to convert fish waste. Combining gravel with plants and decorations, which provide cover and hiding places, will create a healthy and natural environment for your aquatic creatures. The dark color of this fish aquarium gravel will allow the other colors in your aquarium tank, including your colorful fish or other marine animals, to appear brighter and be easier to spot. We recommend a depth of approximately two inches of gravel, especially when used with an undergravel filter. For most aquariums, this amounts to 1.5 to two pounds per gallon of capacity. Keep your aquarium beautiful and healthy with Aqua Culture Aquarium Gravel in Black.