SEACHEM Onyx Gravel 7 kg

Onyx is a specially fracted porous substrate for the aquarium. Onyx is suitable for most marine and freshwater environments including reef and planted aquariums. Onyx is most effective when used alone as an integral substrate bed, but it may be mixed with other gravels or sands. Gravel modifiers are not necessary. Onyx is not chemically coated or treated but does have a slight buffering capacity.