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Fish tank gravel comes in different colors, shapes, and sizes. Purchase gravel that is large and coarse enough to allow water flow, but fine enough to promote the growth of helpful bacteria.  Even if your gravel says “pre-washed,” you should still wash it before adding it to your fish tank. If you're unsure of what kind of gravel would be best for your fish, ask a pet-store employee for help. Open the bag of gravel and pour it into a bucket. Only rinse 5 pounds (2.3 kg) of gravel at a time. If you need to clean more than 5 pounds (2.3 kg) of gravel at a time, clean the gravel in separate batches. It's harder separating the large and small dust and dirt particles from the gravel if you wash more than 5 pounds (2.3 kg) of gravel at a time. The water should rise above the gravel about 1 inch (2.5 cm). Shake the bucket back and forth to swish the water and rinse the gravel. Soaking the gravel will cause dust and dirt to rise to the top of the water and will make the water murky and gray. As you continue the rinsing process, the water should start to become more clear. Tip the bucket over and empty the water while keeping the gravel in the bucket. Then, refill the bucket, let it sit, and pour out the water again. This will ensure that you get all of the loose particles out of the gravel. By the third rinsing, the water should appear more clear. Scoop the gravel into a strainer. Use your faucet or a hose to rinse it down. Continue rinsing the gravel into the strainer until the water runs clear. Then, take the strained gravel and place it in different dry bucket. Straining 1 pound (450 g) of the gravel at a time will make rinsing it more manageable.
Purchase aquarium gravel online or at a pet store. Fill a 5 US gal (19,000 ml) bucket with the gravel. Fill the bucket with cold water and swish the gravel around. Let the gravel soak for 5 minutes. Pour out the water and repeat the rinsing process 3 times. Rinse 1 pound (450 g) of the gravel in a strainer.