1. If you don't already have one, purchase a 5 gallon bucket and label it for aquarium use only. Aquarium buckets should never have soap in them.
2. Place a large clean sieve, at least 6 inches across, over the bucket. Fill the sieve half full of gravel.
3. Pour water over the gravel in the sieve, while gently shaking it. Rinsing the gravel over the bucket rather than over a drain, allows gravel that slips through the sieve to be caught instead of going down the drain.
4.Continue pouring water over the gravel until the water runs clear. Several washings are usually required.
5. Once the water runs clear, the gravel is ready to be used. It may be placed directly into the tank or in a clean bucket or container.
6. Repeat steps three through five until you have washed enough gravel to fill the aquarium three inches deep.