Onyx is a specially fracted porous substrate for the aquarium. Onyx is suitable for any marine or freshwater environments and is ideally suited for cichlid environments. Onyx is most effective when used alone as an integral substrate bed, but it may be mixed with other gravels or sands. Onyx is not chemically coated or treated but does have a slight buffering capacity.
Although pre-washed, it may be rinsed before.
