ONYX GRAVEL 7KG-Onyx is a natural substrate specially spawned for the aquarium. Onyx is suitable for any marine or freshwater environment and is ideally suited for
cichlid environments. Onyx is most effective when used alone as an integral substrate bed, but it can be mixed with other gravels or sands such as Onyx sand. Onyx is not chemically coated or treated but it does have a slight buffering capacity. To determine the number of bags needed for your aquarium, please note that each bag (7 kg) occupies a volume of approximately 7 liters.