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How To Remove Calcium Buildup On Fish Tank | 3 Easy Ways?

Calcium buildup or calcium deposits is a white residue forming on the top of your fish tank. Also known as “limescales” these residue forms because of the evaporation of hard water. Hard water contains a higher mineral content than soft water.

However, hard water is not harmful to your fish when it evaporates calcium carbonate plus additional ions on the glass’s surface, on the hood’s bottom, and even on the filter.

These crusty-looking spots and streaks don’t harm your fish but give your aquarium an awful look. Nobody likes an aesthetically unattractive aquarium. That’s why you should remove calcium deposits on the fish tank/aquarium. Let’s find out How To Remove Calcium Buildup On Fish Tank.

How To Remove Calcium Buildup On Fish Tank

How To Remove Limescale From A Fish Tank

Limescales are so terrible that you’ll have an urge to use home cleaning products to remove them. But, do not use any home cleaning products as those products’ chemicals will likely be lethal for your fish. There are some simple methods to remove calcium buildup from your fish tank.


Vinegar is the most popular method for removing calcium buildup on any surface. Although vinegar is an acid, it doesn’t harm your fish as it is mildly acidic. It will, however, drop your tank’s Ph level to some degree, but you can fix it by using some aquarium-safe Ph Stabilizer. You can get it from amazon.

To clean limescale, you have to remove all the fish, decorations, and gravel from the tank first. Empty the water and apply vinegar to the surfaces that have limescale with a sponge. Let it sit for a few minutes, and then scrub the buildup.

The time frame can go up to one hour, depending on how many calcium deposits formed in your tank. After cleaning your tank, rinse the aquarium, replace the decorations carefully, and refill the tank with freshwater. At last, add your fish to the tank.

Lime Juice/ Lemon Juice

If you don’t have any vinegar at home, you can just use lemon juice or lime juice. They are not as effective as vinegar but still do the job. Follow the exact instructions above to remove calcium buildup from your fish tank.

SAFE & EASY Aquarium Cleaner

If you have a thick layer of calcium buildup on your aquarium that vinegar or lime juice can not remove, you’ll have to use this product. This product is a nontoxic limescale remover made for aquariums and proven to be more effective than vinegar and lime juice.

To use this product, you have to follow the exact instructions of the vinegar cleaning method.

What Dissolves Hard Water Scale?

Hard water scales are actually mineral- deposits buildup on the surfaces of the tanks, taps, and other plumbing fixtures.To remove these deposits, we need to deactivate the minerals with some acidic solution.

To dissolve hard water scales, you can use a commercial tub, sink and tile cleaner that has phosphoric, hydrochloric, or hydroxyacetic acid. All-purpose cleaners are also effective in removing hard-water scales.

These commercial chemicals are not safe to use in aquariums or things that we use for consumption (like glasses, plates, and coffee makers). In this case, you can use vinegar (all types) or lime juice to dissolve and remove hard water scales.

How Do You Dissolve Calcium Deposits Naturally?

Although many commercial cleaners can dissolve calcium deposits, many of us like to stick with natural ingredients.

Vinegar, lemon juice, baking soda, and white wine are effective nontoxic and natural cleaners that naturally remove calcium deposits.

When you mix vinegar and baking soda, you can have better results.

While vinegar lowers the Ph level of water, baking soda raises the Ph level.

Even though it is not a proven formula for aquariums, it can be a perfect solution to dissolve calcium deposits naturally.

How Long Does It Take For Vinegar To Dissolve Calcium Deposits?

That depends on the thickness of the calcium deposit layer. If you have a thin layer, the deposits will dissolve within minutes. But if you have a thick layer of calcium deposits, you will have to soak them with vinegar for hours.

The best way is to not let your goods buildup limescales for long. When you see a thin layer of calcium buildup, clean it right away to avoid the hassle.

What Causes Calcium Buildup In Fish Tank?

When you put mineral-rich hard water into your fish tank, the water evaporates dissolved calcium carbonate, pushes them towards the surface, and deposits them on the tank glass as calcium buildup.

This water evaporation is the leading cause of calcium buildup in fish tanks. To prevent it, you’ll have to use soft water instead.

Does WD 40 Remove Calcium Deposits?

WD40 is a water-displacing spray that can be used for multi-purposes. WD40 can also remove calcium deposits from any surface.

It is actually more efficient than other natural methods. You just have to spray on limescales, set them aside for 4 to 5 minutes, scrub them with a sponge and wipe with a clean cloth. While WD40 is an excellent solution for toilets, tiles, faucets, and other household items, it’s not safe for aquarium use.

What Is The Best Hard Water Stain Remover?

If you are looking for a hard water stain remover for your household items, IronOut Rust Stain Remover is the best choice. Iron Out is the number 1 selling item on Amazon as it’s simple to use, highly effective, and affordable.

If you are looking for a hard water stain remover for your aquarium, SAFE & EASY Aquarium Cleaner is the best choice. Please do not use any household cleaners for your aquarium as they can be toxic to your fish.

How Do You Reduce Calcification of Surfaces?

If you live in an area with hard water in the public water supply, you can not get rid of hard water calcification with any method.

However, you can seal the surfaces using clear resin solvent-based sealers to prevent calcium buildup formation for a considerable amount of days.

How Do You Get Rid Of Thick Limescale?

To get rid of thick limescale, you’ll have to scrub the surface using vinegar or another limescale remover more than two times.

The best way is to cover the surface with a vinegar-soaked towel for at least 2 to 3 hours while keeping the moisture all that time, then scrub the surface to remove limescale.

Credits to MA FishGuy

how to remove hard water stains from fish tank

Hard water stains are mineral-deposits evaporated from mineral-rich hard water. They are also known as calcium buildups, limescale, white residue, and calcium deposits. To remove hard water stains, you have to use an acidic solution.

As it may be toxic for fish, you shouldn’t use any commercial hard water stain remover unless it says ” Aquarium Safe.” The best natural hard water stain removers are vinegar, lime, baking soda, and white wine.

Among these, vinegar and lime juice are recommended for fish tank use. Other solutions may harm the ecosystem of your fish tank. First of all, you have to remove your fish safely to another bucket or a tank.

Then take off all the decorations, substrate, and other equipment from the tank. Now lay the tank down on a towel and pour enough vinegar on the glass’s affected area. Keep it aside for 20 – 30 minutes, and then scrub the surface with a non-abrasive pad or a cloth.

How To Clean Aquarium Glass White Residue?

You can clean aquarium glass with white residue with vinegar, lime, or SAFE & EASY Aquarium Cleaner. First, remove your fish, tank decorations, substrate, and other equipment from your tank safely.

If you are using vinegar or lime, you’ll have to lay the tank on a towel or stick a vinegar or lime soaked towel to the glass and keep it for about 20 to 30 minutes.

Then scrub the white residue with a towel or a non-abrasive pad.  If you are using safe & easy aquarium cleaner, you just have to spray on the white residue and keep it aside for about 4 to 5 minutes. Then wipe the surface with a damp sponge or cloth.

How To Remove Salt Stains From Aquarium Glass?

Salt stains are also mineral deposits evaporated from hard water. If your area’s water source contains hard water, you can not avoid mineral deposits in your aquarium.

To remove salt stains from aquarium glass, you’ll have to use vinegar, lime, or an aquarium-safe glass cleaner. To be on the safe side, you have to remove all your fish, decorations, substrate, and other things from your aquarium and empty the water.

Then, apply vinegar, lime, or aquarium safe glass cleaner, keep it aside for a few minutes, and then wipe the salt stains with a wet towel or sponge.

How To Prevent Hard Water Stains In An Aquarium

To prevent hard water stains in your aquarium, you’ll have to avoid using hard water in your aquarium. You won’t have any trouble of hard water stains with soft water. You can use a home water filtration system to remove minerals from your hard water and add only the required minerals for fish after adding the filtered water to the aquarium.

Another option is to use a natural “water softener” like Sera Super Peat to demineralize the water. Although you may want to get rid of hard water stains by removing minerals from water, your fish may need some of them to thrive. So, before taking a decision, check with your aquatic life requirements first.

Can Demineralized Water Prevent Hard Water Stains?

Yes. Demineralized water can prevent hard water buildup on your aquarium. Demineralized water can also give an aesthetically appealing look to your aquarium, and it is suitable for freshwater fish in your aquarium.

How to Demineralize Water for an Aquarium?

There are mainly two methods to demineralize water for an aquarium.

Using water Softeners

Water softeners like Sera Super Peat use ion exchange resin to exchange calcium and Magnesium for Sodium. Because of this process, softeners remove Calcium and Magnesium from the hard water.

The water may still have other minerals left, so it is not truly a demineralization. However, by using water softeners, you can get rid of ‘hardness’ minerals that can cause limescale buildup.

Using RI DI Systems

With this method, you can get genuinely demineralized water without any minerals. The first process is to filter with a Reverse Osmosis system.

And then, the treated water (called permeate) is processed by De-ionizing filter to remove any leftover minerals. This way, you can ger high purity water for any industrial and commercial purpose; however, you have to re-add essential minerals and bacteria into the water again when you use this purified water for your aquarium.

Why Do You Need Demineralized Water for Aquarium?

The first reason is to avoid the hassle of cleaning calcium buildup or limescale often in the aquarium. Calcium buildup doesn’t cause any problem for your fish, but it reduces your aquarium’s beautiful look.

Because of that single reason, you have to take the hassle of removing all the things with fish from your tank, clean the tank using mentioned cleaners, rinse the tank again and return the items to the aquarium.

With demineralized water, you can avoid doing all that things for good. The second reason is that to confirm that your fish get pure water. Freshwater fish like Bettas need soft water to live. If you put them into hard water, they suffocate. By demineralizing water, you can ensure that your fish get to live in soft and pure water. So, you only have to reintroduce essential minerals back into the water for healthy fish living.

The third reason is that pure water gives an aesthetically appealing look to your aquarium as demineralized water is crystal clear. With crystal clear water, your aquarium shows off everything inside it beautifully, and it also reduces algae buildup, which reduces the look of your aquarium.

Read more Why is my fish tank cloudy after water change: 11 THINGS MUST KNOW

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About Dr.Chamika

Hello, I'm Dr. Chamika. I am a Researcher in Water quality, Aquatic organisms, and Environmental chemistry. I am a passionate fish keeper, with10 years of experience. My mission is to help other aquarists experience the joy of fish keeping.