Features Premium natural substrate for the aquarium Ideal for Tanganyikan Cichlids Rich in carbonates Overview Onyx™ is a specially fracted natural 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 such as Onyx Sand™. Onyx™ is not chemically coated or treated but does have a slight buffering capacity. Onyx™ Mineral Composition Units=mg/kg, source: Plasma Emission Spectrometer, EPA Method 6010, Univ. of Georgia Chemical Analysis Lab Al Ba Ca Co Cr Cu Fe K Mg Mn Na Ni V Zn 822 5 197,500 4 10 4 2,846 417 115,400 43 135 7 8 23 Set-up Although it is pre-washed, because Onyx™ is a natural product, it may become dusty in transit and require rinsing before use to remove any residual dust. When adding water to aquarium, fill slowly to avoid disturbing Onyx™ substrate bed. Place a bowl in the aquarium and add water directly to the bowl, allowing water to overflow softly on to the gravel bed. Initial cloudiness is normal. To remove cloudiness, use mechanical filtration (such as filter floss). Use Clarity™ to accelerate clearing.