How to Remove Calcium Buildup on Fish Tank Systems? – 6 Steps

how to remove calcium buildup on fish tank

Every aquarist or aquatics hobbyist must  khow to remove calcium buildup on fish tank systems. Even folks with water softeners or no calcium carbonate issues in their water should still equip themselves with this knowledge.

Although calcium is not toxic to fish, excessive buildup in fish tanks might indicate nutrient, temperature, and pH issues. Moreover, nobody likes whitish stains on aquarium tops because it detracts from the fish tank’s beauty.

So, how do you clean calcium buildup on fish tank? Continue reading to learn how.

Ways to Remove Calcium Buildup

What to prepare

You need the following items to remove limescale from aquarium glass and other components.

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  • Weak acid (vinegar, lemon/lime juice, or a commercially available calcium remover)
  • Scrubber, brush, or washcloth (must be non-abrasive)
  • A siphon (optional)
  • Fish net
  • Plastic cup
  • Large bowl for fish
  • Large container for accessories
  • pH test strip and pH stabilizer


Step 1: Ensure clean hands.


Make it a habit to clean or wash your hands before and after working with a fish tank. This is because your hands contain germs that can mix with the fish tank water and make your aquatic friends sick.

In a similar vein, aquarium water is not the “cleanest” because it contains fish poo, algae, leftover fish food, and other organic substances. As such, never forget to wash your hands after you get rid of calcium deposits.

Step 2: Remove all accessories and decorations.

Some folks skip this step because the limescale (calcium) buildup occurs mostly near the fish tank’s top edge. However, we recommend emptying the fish tank to ensure a more thorough cleaning of calcium deposits.

Disconnect aquarium filtration systems, UV lights, heaters, bubblers, and other electronic devices and accessories. Place these objects in a large container so you do not lose them.

Remove all decorations to make cleaning calcium deposits in the fish tank easier.

Step 3: Remove 50% of the water and reserve it.


Use a plastic cup to scoop water from the fish tank and transfer it to a large container or bowl. This container serves as a temporary shelter for your fish and “live” aquatic plants while removing calcium buildup from the aquarium.

Remove and reserve only half of the aquarium water to maintain the ideal water pH and temperature when adding new water after cleaning the limescale buildup off the fish tank.

A faster way is to use a siphon.

Step 4: Relocate fish and aquatic plants.

We recommend relocating your fish to the large container or bowl with the reserved fish tank water removed in Step 3.

Use a soft fish net to gently scoop the fish from the aquarium. Take your time to avoid stressing your fish. Alternatively, a plastic cup can help.

Step 5: Empty the aquarium and remove calcium buildup.


Go to the sink and tip the aquarium over to drain the water. Pour the fish tank substrate into a sieve or strainer to prevent it from going down the drain.

Step 5.1: Using vinegar


One of the most effective homemade calcium remover is vinegar. It is a weak acid, making it relatively safe for your fish.

Using vinegar to remove calcium build up in fish tanks requires dabbing a clean piece of cloth in vinegar. Apply the vinegar to the calcium buildup.

You can also pour vinegar into the aquarium until it covers the limescale. This trick is effective for stubborn calcium buildup.

For both tricks, leave the vinegar for about 10 to 20 minutes before scrubbing the limescale buildup with a soft washcloth or scrubber.

Step 5.2: Using lemon or lime juice


Another worthy homemade fish tank calcium remover is lemon or lime juice. This technique is especially advantageous for people who do not like the smell of vinegar.

Similar to vinegar, citrus juice is also a weak acid. It’s fish-safe and can remove mild calcium buildup, albeit not as effectively as vinegar.

Simply apply the lemon/lime juice over the calcium buildup and leave it be for 20–30 minutes. Afterward, wipe the tank with a soft washcloth.

Step 5.3: Using a commercially available calcium remover

A commercially available calcium build up cleaner is an effective alternative to vinegar, lemon juice, and lime juice.

Some products can “melt” stubborn calcium deposits without harming the fish. However, homeowners must read the active ingredients to ensure it does not contain citric acid.

Although citric acid makes it easier to remove calcium deposits, it “denatures” protein molecules. Citric acid is also a herbicide that might harm aquatic plants.

Ideally, you should follow the product’s instructions. If there isn’t any, apply the product directly over the calcium and let it sit for half an hour before wiping the tank clean.

Step 6: Rinse the tank and return everything.


Although calcium removers are fish-safe, you will still want to rinse the fish tank thoroughly. Return the decorations and fish tank appliances.

Pour the reserved water into the aquarium and add enough new water to fill the fish tank. Check the pH level because the cleaning solutions are acids, and you do not want the water to be too acidic.

Add a pH stabilizer to balance the pH before returning the fish, if necessary.

Frequently Asked Questions


Why does calcium buildup on fish tanks?

The white buildup on fish tank filter and glass are calcium carbonate molecules that adhere to surfaces through one of four mechanisms.

  1. Calcium carbonate precipitation can occur due to a water pH level higher than 7.5.
  2. Hard water levels higher than 120 ppm or 7 grains per gallon can also favor calcium buildup on aquarium glass and other surfaces.
  3. Low carbon dioxide levels in the fish tank water make limescale formation more likely.
  4. Increased fish tank water temperature can promote the chemical reaction between carbonates and calcium ions to form calcium carbonate.

Is calcium buildup harmful for fish?

No, calcium buildup is not harmful to fish. However, it is worth noting that limescale formation in fish tanks is a sign of nutrient and pH imbalance in the aquarium ecosystem.

Increased calcium in the water favors a chemical reaction with bicarbonate ions to form calcium carbonate. Too much sunlight reduces carbon dioxide in the water by channeling the molecule to plants for photosynthesis, which ultimately increases calcium carbonate as well.

How to prevent calcium buildup on fish tank?

Observe the following tips to prevent calcium buildup in aquarium systems.

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  • Use demineralized water for the aquarium. You can also install a water softener, depending on the fish species.
  • Avoid adding calcium-rich corals and “chalky” aquarium decorations.
  • Clean fish tank filter cartridges at least once weekly.
  • Add soft water to the fish tank daily.
  • Observe correct fish feeding practices to maintain the ideal pH and nutrient balance.
  • Keep your aquarium away from direct sunlight to prevent carbon dioxide reduction and water temperature spikes.


Clean calcium off the fish tank at the first sign; do not allow it to grow.


You now know how to remove calcium buildup on fish tank systems. The procedure is like cleaning and changing the water of an aquarium, except you need a calcium remover.

You have three options: vinegar, lime/lemon juice, and a commercially available product. The steps are similar – relocate the fish, empty the tank, apply the weak acid, leave it for several minutes, scrub it off, and rinse.

It should be easy to remember and learn by heart.