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.
Why not use the Gravel Calculator at www.seachem.com to make sure you get the correct amount of substrate