How to Clean an Old Fish Tank

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Using an old fish tank is a great way to provide the right home for your fish without the expense of purchasing a new tank. For your fish to thrive and survive, it is important that your old fish tank is properly cleaned and sanitized. By emptying the tank, sanitizing the glass, and washing all the tank decorations, your fish will have a like-new home that is clean and safe!

Cleaning a Second-Hand Fish Tank with Vinegar

Mix equal parts water and white vinegar in a spray bottle. Spray the sides of the empty tank thoroughly with the mixture and wait 10-15 minutes. Rinse the tank out with water and let it air-dry for 24 hours. Remove any remaining white residue or hard water buildup with a razor blade or scrubbing pad.

Part 1
Part 1 of 3:

Emptying the Tank

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  1. Using your hands or a fish net, remove everything from the fish tank that isn’t permanent, including all decorations, plants, rocks, and gravel. This will let you properly clean and sanitize the tank.
    • If you plan to clean and reuse these items, set them aside to be sanitized separately.
    • If the gravel is too difficult to remove by hand or fish net, you may need to use a gravel siphon vacuum to get it all out.
  2. If the fish tank is relatively small and easy to carry, you can lift the tank and pour any remaining liquid into a bucket or sink. If the tank is too large to lift, place a large bucket on the ground next to the tank and gently tilt the tank so that the water slowly falls into the bucket.
    • Make sure that you use a bucket that is large enough to hold all the old water in your tank. You want to drain it completely. For example, if your fish tank holds 4 gallons of water, you will likely want to use at least a 5-gallon bucket to avoid spillover.
    • If the fish tank is very large, you may need to use a siphon hose to drain the water into a bucket or sink. [1]
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  3. Lightly dampen a paper towel with warm water. Wipe the interior and exterior sides and bottom of the tank with the lightly dampened paper towel to remove dirt and residue.
    • Wiping away the more easily removed dirt and residue will make it easier to sanitize the tank and identify any white residue due to lime or calcium build up, or hard water spots that will need to be scrubbed or scrapped clean.
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Part 2
Part 2 of 3:

Sanitizing the Glass

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  1. It is important that you use a safe cleaning solution so that your old fish tank is properly sanitized. [2] There are several cleaning solutions that you can mix up to effectively and safely clean your old fish tank. Try mixing:
    • Equal parts water and vinegar in a spray bottle. A vinegar and water cleaning solution is excellent for breaking down white residue or hard water stains, neutralizing fishy odors, and safely sanitizing your old fish tank. Add vinegar and water to a clean spray bottle, alternating each to ensure that you have equal parts. Shake vigorously for 10 seconds to combine.
    • 1 part non-detergent bleach to every 9 parts water in a spray bottle. When used in proper concentrations, bleach is perfectly safe to use to clean an old fish tank. For fish safety, it is important that your solution does not exceed 10% bleach. For example, mix 2 ounces (57 g) of bleach with 18 ounces (510 g) of water in a spray bottle. Shake vigorously for 10 seconds to combine.
  2. Generously spray to ensure you cover all the surfaces of the tank with the cleaning solution. Make sure to spray inside and around any items that may be attached to the tank.
    • When spraying the outside of the tank, make sure that the tank sits on a bleach-safe or vinegar-safe surface, depending on which solution you choose to use.
  3. If you are using bleach, make sure that you do not leave the cleaning solution on the fish tank for more than 15 minutes. Bleach is a corrosive chemical and can cause permanent damage to your old fish tank if left too long. [3]
    • If you are using a vinegar solution, it is safe to leave the solution on for longer. You can leave a vinegar and water solution on for up to 48 hours without causing harm to your fish tank.
  4. Fill the tank with clean water and let it soak for 10 to 15 minutes. After the clean water has soaked, drain by slowly tipping it into a large bucket or sink, or by using a siphon hose.
  5. Once the fish tank is drained, let it air dry for 24 hours. This allows any remaining bleach or vinegar to break down, leaving it safe for your fish. [4]
  6. Using a razor blade or a fish tank safe algae scrubbing pad, scrub and scrape any remaining residue or hard water stains from the walls and bottom of the tank. Once you have scrubbed and scrapped all remaining stains, use warm water and a paper towel to remove any excess debris from the tank.
    • Be sure to use caution when scrapping with a razor blade. Always point the blade away from you with light to medium pressure to avoid scratching the glass.
    • If safety is a concern, you can use an acrylic or plastic razor blade instead of a metal blade. An acrylic or plastic razor blade is less sharp than a metal blade, but should still be effective in removing lime, algae, and calcium build up or hard water stains. [5]
    • If you scrapped a lot of debris into the fish tank, you may need to re-rinse the tank with water to ensure the tank is completely clean for your fish.
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Part 3
Part 3 of 3:

Washing the Removable Tank Decorations

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  1. After you’ve cleaned and sanitized the glass in your tank, you will want to sanitize any tank decorations you plan to reuse.
    • Place all the removable tank items on a vinegar or bleach-safe surface.
    • Spray all the items generously with the cleaning solution and let them soak for 10 to 15 minutes.
    • After the soak, rinse the items under running water to remove all the vinegar or bleach. Let them air dry for 24 hours.
    • You can also mix your vinegar or bleach solution in a large bleach-safe bucket or sink and let the removable tank items soak submerged for 10 to 15 minutes.
  2. Using a fish-safe scrubbing pad, scrub any items that have any remaining build-up, dirt or debris. If the item is small or has hard-to-reach spots, you can use a clean, new toothbrush to help reach into crevices.
    • Rinse the scrubbed items under running water. Pat dry with a clean paper towel or let air dry completely.
  3. Once the tank and all the items have been cleaned, you are ready to reassemble your old fish tank and provide a safe and sanitary home for your fish.
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How Do You Clean a Fish Tank?


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      Things You’ll Need

      • Clean water
      • 2-3 buckets
      • New spray bottle
      • Algae or fish-safe scrubbing pads
      • Razor blade
      • Non-detergent bleach or vinegar and salt
      • Siphon hose

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      Warnings

      • Never use soap or detergent to clean your fish tank or any of the items that go in it. Both are highly toxic to fish and even a small amount of residue left over after cleaning can be deadly.
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      References

      1. ↑ Craig Morton. Aquarium Specialist, Aquarium Doctor Inc.. Expert Interview. 21 July 2020.
      2. ↑ https://pethelpful.com/fish-aquariums/How-To-Safely-Clean-A-Second-Hand-Fish-Tank-or-Aquarium
      3. ↑ https://nippyfish.net/2009/03/30/how-to-disinfect-sanitize-your-aquarium-with-bleach/
      4. ↑ https://www.thesprucepets.com/is-bleach-safe-for-aquarium-use-1381085
      5. ↑ https://storiesofwater.com/how-to-clean-a-used-fish-tank/
      6. ↑ Craig Morton. Aquarium Specialist, Aquarium Doctor Inc.. Expert Interview. 21 July 2020.
      7. ↑ Craig Morton. Aquarium Specialist, Aquarium Doctor Inc.. Expert Interview. 21 July 2020.

      About This Article

      Article Summary X

      To clean an old fish tank, first remove all the decorations and other removable items from the tank. Empty all the old water out into a bucket or sink. Next, use a paper towel dampened with warm water to wipe down the walls and bottom of the tank. Mix up a solution of equal parts water and vinegar in a spray bottle and spray down the interior and exterior of the tank with it. Let it soak for 10-15 minutes before rinsing the tank with fresh, clean water. Let the fresh water sit in the tank for another 10-15 minutes before draining it into a bucket or sink. Allow the tank to air dry for at least 24 hours, then use a fish tank-safe algae scrubbing pad or a razor blade to scrape away any stubborn residue or hard water deposits. Wipe away the loose gunk with a damp paper towel. Depending on how much residue you loosened, you may need to rinse the tank again. Clean any removable decorations or equipment with your vinegar cleaning solution and a scrubbing pad, then rinse them carefully before putting them back in the tank.

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