How to Clean Fish Tank Rocks

Co-authored by Aaron Bernard

Last Updated: December 26, 2022 References

Uneaten food and fecal matter can settle in the bottom of your fish tank, making your gravel grimy. Periodically removing this waste and debris creates a healthier environment for your fish. Whether you have a small tank with just one goldfish or a large tank with many exotic fish, you can clean your aquarium gravel at home and keep your fish happy and healthy.

Method 1

Method 1 of 3:

Washing Gravel in Small Tanks

1
Remove your fish from the tank. If you have a single small fish, such as a goldfish or a betta, it is easier to remove it from the tank for gravel cleaning. Fill a clean container as close to the size of your fish tank as possible with non-chlorinated water. Use a drinking glass or a fish net to gently move your fish from the tank to the container.^{[1]
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2
Remove the accessories from your tank. Unhook your water filter, and remove any plants or decorations from your fish tank. Set these aside. The tank should be full of only water and gravel before you begin cleaning.^{[2]
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3
Rinse the gravel with treated water. Gently pour the water from your fish tank through a colander. Under a stream of lukewarm water, agitate the colander to loosen and wash away any stubborn debris. Do this several times until the water coming off your gravel runs clean and clear.^{[3]
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4
Replace the gravel on the floor of the tank. When the gravel is clean, spread it evenly back over the bottom of your fish tank. Reattach your water filter and set up any decorations as desired.
5
Set your tank back up. Refill your fish tank with non-chlorinated water.^{[4]
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Research source} If your breed of fish necessitates any other particular requirements, such as water of a certain pH, treat your tank accordingly. When everything is in place, gently submerge your fish and its holding container in the tank, letting your fish swim free.
- Consult your local pet store for more information about the water requirements of your particular fish.

Method 2

Method 2 of 3:

Washing Gravel in Large Tanks

1
Do not remove your fish from the tank. If you have many fish or exotic breeds, do not remove your fish from the tank for gravel cleaning. Doing so for the extended period of time required to clean a larger tank can be stressful for the fish. It’s also not necessary when using a gravel siphon, a special gravel-cleaning tool for larger tanks that you are going to use.^{[5]
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2
Place a plastic bucket on the floor near the tank. Buy a clean bucket that you only use for fish tank maintenance. Place it at a lower level than the aquarium so gravity can do most of the work for you.^{[6]
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- Do not use a household bucket that might have chemicals from prior cleaning projects. Although you are only using this bucket to discard fish water, it’s really best to keep your pet’s supplies separate to avoid confusion.
3
Position the gravel siphon. Place the cylinder end of the gravel siphon in the tank, such that the opening is resting at the bottom in the gravel. Guide the plastic tubing at the other end over the edge of the tank, holding it in your hand over the waiting bucket.^{[7]
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4
Suck on the tubing end of the gravel siphon to create negative pressure. Immediately place the end of the tube in the waiting bucket after doing this. As soon as you suck, negative pressure will be created in the tube, and dirty fish tank water will flow through the tubing to the bucket. This is what you want but be careful not to suck too long, as you might get a mouthful of aquarium water.^{[8]
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- If you can’t stomach sucking on the tubing, some siphons make special priming balls that start the siphon for you. Seek one out at your local pet or aquarium store.
- If you do end up drinking a little water, rest assured this is not harmful.
5
Use the cylinder end of the siphon to remove debris. Once the siphon is going, you don’t need to do anything to maintain the pressure. While the water flows freely, press the open, submerged end of the siphon down into the gravel. Move from one end of the tank to the other, pressing the mouth of the siphon down into the gravel with a circling motion to vacuum up debris.^{[9]
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Research source} The suction may lift a piece of gravel or two into the cylinder of the siphon, but it will not be able to suck it into the tubing; simply shake loose any gravel bits that rise up.^{[10]
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- You should see matter being sucked out of the gravel as you work. If you don’t, press the opening deeper into the gravel.
- As you move the siphon about the tank, be careful not to bump or frighten your fish. Work slowly.
6
Do not drain more than 25% of the water from the tank. Doing so can upset the balance of good bacteria in the tank. Plus, your fish are still in there, and they need it even though you’re cleaning.^{[11]
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7
Discard the dirty water. Once you have vacuumed the gravel to your satisfaction, remove the gravel siphon and set it aside. Discard the dirty water in the bucket by pouring it into your sink or into your toilet. Wash the siphon in hot water.
8
Refill your tank. Once gravel cleaning is complete, refill your tank to its normal level with non-chlorinated water.^{[12]
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Research source} If your fish have any special requirements, such as PH adjustments, be sure to perform those as well.

Method 3

Method 3 of 3:

Maintaining Your Aquarium Gravel

1
Change your aquarium filter per the manufacturer’s directions. Keeping on top of water-filter changes will prevent your gravel from collecting extra grime. Make a calendar reminder to help you remember to change it regularly.
- It can be helpful to let your new and old aquarium filters run in tandem for a couple days to keep from changing the ecosystem of your tank too rapidly.^{[13]
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2
Clean your gravel every two weeks. Clean your gravel every other week to maintain the health of your fish and your tank. Doing so more often is unnecessary and may remove beneficial bacteria from the environment.^{[14]
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3
Avoid using detergents or harsh cleaners. Most commercial cleaning solutions are toxic to fish. Always wash your gravel with plain, non-chlorinated water. If your gravel is so dirty that these methods are not cleaning it, buy new gravel rather than trying a stronger solution.^{[15]
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Expert Q&A

Question

How often should I clean my tank water?

Aaron Bernard
Fish & Aquarium Specialist
Aaron Bernard is an Aquarium Specialist and the Owner of Limited Edition Corals in Phoenix, Arizona. With over ten years of experience, Aaron specializes in aquarium maintenance, custom design, manufacture, installation, and moving. Aaron holds a BS in Biochemistry from Arizona State University, where he studied the effects of climate change on coral reefs and began to propagate his corals.

Aaron Bernard

Fish & Aquarium Specialist

Expert Answer

I recommend doing a 25% water change about once a month to keep your tank clean without removing too much of the healthy bacteria.
Question

Do these methods also help get rid of the bad smell in the gravel?

Community Answer

Yes; it gets rid of the algae, which usually causes the smell.

Warnings

It's not necessary to wash gravel all the time. It can actually be detrimental to the bacteria living on the substrate, and disturbing rooted plants while removing their nutrients is not good. Only wash if you need to.

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Never wash gravel with soap.

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