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How to Clean a Fish Tank: Remove That Nasty Smell

Learn how to clean a fish tank so you can keep your fish healthy.

Tropical fish swimming around a clean aquarium is a beautiful sight. The bright colors of the fish gleam in the water against the rocks, plants, and decorations. It’s important to be able to maintain the health of your fish without your tank beginning to stink or developing cloudy water due to algae.

So here’s a guide for beginners on how to clean a fish tank.

Key Takeaways

  • Clean fish tank regularly to maintain a healthy environment for fish; partial water changes are needed weekly for average and large tanks.
  • Don’t use soap or any harmful chemicals to clean fish tanks, and leave the fish in the tank during the cleaning process.
  • Use a gravel vacuum or siphon to clean gravel, change dirty water, and clean glass walls, rocks, plants, and decorations without removing fish.
  • Maintain a regular cleaning schedule, use proper filtration, and avoid overfeeding to prevent the tank from getting dirty quickly.

How Often Should I Clean My Fish Tank?

A clean fish tank is important for maintaining the beauty of the tank, ensuring the filtration system works properly, and for the health of your fish.

How often you need to clean your fish tank depends upon the size, number of fish, and filtration system of your tank. An average size or large fish tank will need weekly partial water changes.

Keep an eye on your tank. It will need to be cleaned when you see cloudy water, your fish behaving abnormally, or gasping for air.

Check the pH, nitrate, and ammonia levels regularly to make sure they remain at the same level.

Do You Take the Fish Out of the Tank When Cleaning?

When cleaning a fish tank, you will not be replacing all the water in the aquarium as this removes beneficial bacteria and resets the nitrogen cycle causing undue stress to the fish. Removing your fish also runs the risk of harming them and causes them unneeded stress.

So, you should leave the fish in the tank when cleaning it.

Can You Use Soap to Clean a Fish Tank?

Even a small trace of soap is deadly to fish, so never use soap to clean the tank. Other products such as air fresheners, hand sanitizing gels, and insecticides are dangerous as well.

How to Clean a Fish Tank Without Removing the Fish

Before you begin cleaning the tank, make sure you unplug the heater and filter. This will ensure you can safely clean the tank without giving yourself an electric shock. After you’ve finished cleaning your tank, plug them back in.

  • Time: 1 hour
  • Difficulty: Beginner

What You’ll Need

Clean the Glass Walls

1. Scrape Algae

If you have a glass tank, use a metal scraper to remove the algae from the inside walls of your tank. An acrylic tank requires the use of a plastic scraper so you don’t scratch the sides.

Scrape the walls until the algae have been removed.

2. Rinse Lid

If there are algae on the lid, rinse the lid under running hot water. Use a toothbrush to scrub the lid and remove stuck-on bits of algae.

Clean the Gravel

Cleaning the gravel in the aquarium using siphon

1. Rake the Sand

Use your fingers to gently rake the sand. You’re moving the debris and feces to the top of the sand to make it easier to remove the debris.

Be careful not to stir up the sand too much. Deep sand beds can develop hydrogen sulfide gas which might kill your fish if it’s released too quickly.

2. Vacuum or Siphon the Gravel

Now, use a gravel vacuum or siphon to remove the water and debris and put it into a bucket.

Start by holding the end of your siphon or vacuum about 1-2 inches over the sand. A gravel vacuum will have a valve to control the flow. If you’re using a siphon, you can pinch the tube.

As the sand rises, move the siphon or vacuum up and away from the sand. The sand will return to the bottom of the tank, but the debris will be sucked up and into the bucket.

Move the vacuum or siphon all over the tank removing the debris. Stop when you’ve cleaned the entire floor of your tank or removed half the water.

Don’t worry if you haven’t cleaned the entire tank. Start where you stopped the next time you clean the tank.

Change Dirty Water

1. Remove Water

About half of the tank’s water should have been removed. This is important as it allows the beneficial bacteria in the tank to remain and doesn’t disturb the nitrogen cycle.

Pour the old water out of the bucket. It’s excellent for watering indoor and outdoor plants.

2. Fill Bucket With Fresh Water

Turn on the faucet and adjust the water temperature until it’s the same temperature as the water in the tank. Because human hands can detect temperatures within 1 or 2 degrees, you’ll have the correct temperature for your fish.

Fill the bucket with the tap water.

3. Condition the Water

Use a conditioning treatment to remove the water. Read the label on your water conditioner and follow the instructions to dose the water. This will ensure that the water is safe for your freshwater fish.

Take Note

The old recommendation was to leave the tap water out for 24 hours and allow the chlorine to evaporate. However, chloramine, a more stable form of chlorine, is now commonly used in tap water. It doesn’t evaporate so the water must be dosed to remove chlorine.

4. Add Water

Carefully and slowly add the water back into the tank. You can use a bleached and well-rinsed pitcher to transfer the water from the bucket into the tank so that the fish aren’t disturbed by a sudden rush of water.

Clean the Outside of the Tank

Male cleaning the outside of aquarium fish tank

1. Outside Tank Walls

Spray a microfiber cloth with an aquarium-safe glass and acrylic cleaner. It’s important to make sure the cleaner is aquarium safe so you don’t poison your fish.

Wipe the outside tank walls with a damp cloth.

2. Scrub

Scrub the water spots and smudges with the microfiber cloth.

3. Clean Lid, Light, and Stand

Use the microfiber cloth to remove the dust that has collected on the lid, light, and stand.

How to Clean Rocks, Plants, and Decorations

Clean the rocks, plants, and decorations in your tank when they begin to look dirty, as the buildup of algae on the items creates an unhealthy environment for your fish.

  • Time: 2 hours
  • Difficult: Beginner

What You’ll Need

1. Remove

Remove the rocks, plants, and decorations from the tank. Be careful when removing plants so that you don’t damage the roots.

2. Scrub

Scrub the rocks, and decorations under hot water. Use a clean toothbrush to get into the crevices and remove the algae.

Carefully rinse the plants under lukewarm water and gently scrub them with your fingers to remove any algae on the plants.

3. Soak

If you’re unable to remove the algae from the rocks, decorations, and plants you can soak them in a diluted mixture of bleach and water to remove the stubborn algae buildup.

Measure 19 cups of water into a bucket and add 1 cup of bleach. Add the decorations and soak them in the solution for 15 minutes before removing them.

4. Rinse

Rinse the items carefully under running tap water. Allow the decorations to air dry.

5. Soak in Dechlorinated Water

Fill the bucket with water and add the appropriate amount of water conditioner. Follow the instructions on the label. This will ensure that the chlorine has been removed.

6. Replace in Tank

Carefully replace the items in your fish tank.

How to Clean a Fish Tank Filter

Your fish tank filter will need to be cleaned about once a month or every 4 weeks.

  • Time: 30 minutes
  • Difficult: Beginner

What You’ll Need

1. Inspect Filter

Unplug and remove your filter. Before you begin cleaning, inspect the filter to make sure that all the parts are working properly.

2. Soak Filter

Fill the bucket with cool water. Follow the instructions on the label to add water conditioner to the water.

You will need to make sure that the water is cool and that all the bleach and chemicals have been removed otherwise the water will kill the beneficial bacteria that should be maintained for the health of your fish tank.

Remove the filter from the aquarium and place it in the bucket of dechlorinated water.

3. Scrub Filter

Use an algae pad and the dechlorinated water or water from the fish tank to scrub any areas that have algae buildup on non-media parts of the filter.

If you have a biological filtration, the media should not be replaced, rinsed, or disturbed as this may destroy the helpful bacteria inside it.

Sponge filters and filter pads may be rinsed or replaced.

Chemical filtration systems such as carbon should be replaced every 3-4 weeks.

4. Replace Filter

Replace the filter in the tank and plug it in.

How to Clean an Empty Fish Tank With Vinegar

If you’re about to put an empty fish tank into storage, you can give it a good scrub with vinegar. Make sure you don’t use soap as any trace of soap left in the tank will kill future fish.

  • Time: 1 hour
  • Difficult: Beginner

What You’ll Need

1. Empty Tank

Make sure the tank is empty.

2. Rinse Tank

Dampen the sponge with tap water. Wipe down the inside and outside of the tank to loosen and remove any algae and calcium deposits. Be careful not to scratch your tank, especially if it’s an acrylic tank.

3. Scrub Tank

Rinse your sponge, then sprinkle table salt on it. Wipe the tank again gently scrubbing it with the salt. Focus your attention on any stubborn stains.

You can leave the salt on the stain for a few minutes to help it lift off the tank, but make sure you don’t allow the salt to completely dry before removing it.

4. Rinse Tank

Put your fish tank in the bathtub or outside on the grass. Rinse the tank out entirely in the tub or with a hose.

5. Remove Stubborn Stains

If you have a glass tank, you can use a razor blade to carefully scrape off stubborn stains. Make sure you don’t cut yourself. Skip this step if your tank is acrylic or you have grass stains on it.

6. Clean With Vinegar

Clean your tank with vinegar by mixing 1 part tap water and 1 part vinegar in a bowl. Dip the sponge into the solution and squeeze it out. Scrub the entire tank, inside and out, to remove all the algae and calcium stains.

7. Rinse

Rinse the tank thoroughly. Allow it to completely air dry before putting the tank into storage.

Why Does My Tank Get Dirty So Quickly?

Sometimes you’ll find that your fish tank gets dirty extremely fast. This may be the result of the following conditions.

  • Your tank is too small for the number of fish. The fish become stressed and create more waste than normal.
  • You don’t have the right filtration system. It needs to be large enough to filter the tank.
  • The fish may be overfed. This causes the fish to create more waste. In addition, the excess food lingers in the water and promotes algae growth.
  • The tank is receiving too much light or you’re leaving the light on for too long. Light also encourages algae growth.
  • The pH balance may be too low causing the algae to thrive and multiply.

Fish Tank Maintenance Tips

  • Make sure you’re using the right size fish tank for the number of fish you have.
  • Don’t overfeed your fish.
  • Change the water regularly.
  • Clean your tank with a filter and make sure it’s the best one available.
  • Add a snail or shrimp to your tank to help remove algae.
  • Maintain a regular cleaning schedule for your fish tank.


How Big Should Your Fish Tank Be?

The size of the tank depends upon the size and number of your fish. Here’s a rough guide you can use.

  • 1 small fish needs a 5-gallon tank.
  • 5 small fish need a 10-gallon to a 20-gallon tank.
  • 6-12 small fish will need a 21-40 gallon tank.

How Do You Clean Fish Tank Gravel Without a Vacuum?

Use a siphon instead of a gravel vacuum to clean the gravel in your fish tank.

How Do I Keep My Fish Tank Clean Naturally?

You can use shrimp, snails, or oysters to help keep your fish tank clean naturally. They will eat the algae in the tank and help to keep it clean.

Is It OK to Have 2 Filters In a Fish Tank?

Yes, you can have 2 filters in your fish tank if your tank is large enough.

Why Is My Fish Tank So Smelly?

A fish tank may become extremely smelly due to the odor of decomposing material in the tank. This may be the result of a dead fish, a rotting plant, or overfeeding your fish.

Can You Change Fish Tank Water Too Often?

Knowing if you can change fish tank water too often depends on getting the right balance between filtration and good bacteria on solid surfaces.

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About the Author

Sara Dennis

Sara Dennis is a coffee-loving freelance writer, homeschool blogger, and mom of six kids. In her free time, Sara loves reading books and researching more efficient and effective ways to keep a clean house, homeschool her children, and blog better while making a home for her large family.