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How To Remove Calcium Scale From A Pool (Plaster, Tile, Liner)

Having your own pool can not only make your backyard more fun, but also add a touch of class.

But if a regular maintenance schedule isn’t adhered to, your luxurious oasis can begin to look run-down, with calcium scale buildup being a common problem.

In order to restore the pool to its former glory, you’ll have to learn the proper pool calcium removal techniques.

What Is Calcium Pool Scale?

Calcium pool scale is a chalky-looking film of calcium deposits that build up on your pool finish if your chemistry levels or pH balance is out of whack, or you have an abundance of calcium (high calcium hardness) in the water.

An increase in calcium hardness levels can occur after adding it to the water, or the water taking it from anywhere it can find it (usually from the pool’s plaster finish).

It can occur throughout the entire structure, but it’s most commonly found along the waterline. This is due to calcium deposits being left on the pool’s surface after water has evaporated.

Scaling usually forms in the warmer areas of the pool first – sunny spots, spillways/shallow areas, heat exchangers, and salt cells. Pools that are finished with dark tiles and stones will also keep the pool water warmer and are prone to scale.

In some cases, calcium scaling can affect the pool’s pipes, and it can even show up on pool water features, as they usually require extra maintenance by hand to keep clean.

There’s two types of calcium pool scale you may encounter: calcium carbonate, and calcium silicate.

Calcium Carbonate

As a dietary supplement, calcium carbonate is great for keeping your bones strong, and your body healthy. As a mineral in your pool, it doesn’t quite have the same charm. 

Calcium carbonate is the most common form of calcium scaling that accumulates at the waterline. White and flakey, calcium is left behind after the evaporation of pool water. Removing this type of pool scale is fairly straightforward and simple.

Calcium Silicate

White-grey in color, this is the pool scale you don’t want to have to deal with. 

If your pool has a problem with calcium silicate, you’re most likely going to have to call a professional to get rid of it. That’s because this calcium scaling becomes an issue not only in your pool, but also in the pipes and filtration system. 

Professional pool companies will have the proper chemicals that are needed to fully remove it.  

By using muriatic acid, you can easily test and find out which calcium deposit you’re dealing with. Apply a few drops of the acid directly on the calcium. If it fizzes and bubbles, you have the “good” scale – calcium carbonate. If there’s no reaction, it’s calcium silicate.

Why Is Calcium Scale A Problem?

Aside from being an eyesore that detracts from the beauty of your pool, calcium buildup and scaling can lead to long-term damage.

As mentioned, the pH level of the pool has to stay balanced to keep calcium levels from spiking and scale from forming. When the water is too saturated with calcium, it causes calcium deposits that appear as nasty pool stains and cloudy water.

On the flipside, low calcium levels will lead to water actually corroding your pool’s finish. Etching will result if you have a plaster finish, and the water will literally eat through fiberglass or vinyl liner as it searches for calcium to balance itself.

How To Remove Calcium Scale From Your Pool

Depending on your situation, pool calcium removal can be tricky or relatively easy, and there are a few techniques you can use to restore your pool finish so it looks brand spankin’ new.

Note: These techniques apply only for calcium carbonate scale. Silicate scale will require professional help for removal.

Pumice Stone 

A little grit and a lot of elbow grease go a long way. Using a pumice stone is a common way to get rid of calcium scale that has built up on the waterline. 

With this technique, you should only ever use it on ceramic and concrete surfaces, as the stone can scratch/damage fiberglass walls, glass tiles, or vinyl liner.

Removal is done by first draining the pool a few inches below the scale line. Keeping both the pumice stone and pool wall wet, rub the stone against the wall in slow, circular motions until the scale is removed.

Stain Eraser Brush

A stain eraser brush is a type of pool brush that uses the same technique but is gentler for use on a wider variety of pool finishes. 

If there is very little calcium build up, you may be able to remove it with only the brush. But in most instances, you’ll likely need to add a scale removing agent to first soak the scale, making it easy for the brush to then remove it.

Scale Remover Chemicals

There are various scale removal chemical products to help get rid of calcium build up. 

Most common are a spray-and-soak type of remover. Others are chemicals that are added to the pool, and over the course of several weeks they help dissolve any existing calcium deposits.

Of note, whenever you are using a chemical removal product, be sure that it’s compatible with your pool water’s chlorinated or non-chlorinated nature and won’t severely upset the water balance.

Removing Scale From Specific Pool Surfaces

As pool finishes vary, let’s look at the safest way to remove scale from each of them.

Removing Calcium Scale From Plaster

The best way to get rid of scale from plaster will be with a stain eraser brush. For caked on scale, you may need to add a chemical agent to lend a hand. Regularly brushing your plaster pool walls will also help to keep calcium from building up.

If your plaster is white, you might have a hard time even seeing the buildup. Darker pool plaster colors may be more difficult to fully remove the scale. For these situations, acid washing by a professional may be the best answer.

Removing Calcium Scale From Tile

Tile can be a bit tricky for calcium scale removal, as it’s a bit more delicate to work with.

Some people recommend scraping them with a putty knife or razor blade. Some will even use a hammer to chip away at the scale. 

While these techniques do work, the possibility of damaging your expensive pool tiles using these methods is extremely high.

It’s for this reason we recommend using a stain remover brush and chemical agent combination for pool tiles.

Removing Calcium Scale From Vinyl Liner

Calcium stains can leave a lasting impression, especially on vinyl liners. 

The good news is that vinyl liners are one of the easiest finishes to keep clean, but the bad news is that they’re also very delicate so you have to be careful not to damage them.

Cleaning them with a soft brush (or even just a sponge) as well as a stain removing agent is ideal.

How To Prevent Pool Scale

The best way to prevent pool scale from becoming an issue is to not let your pool water become unbalanced. This means regular water testing, and adding or removing chemicals to keep the pH at a balanced level between 7.2 and 7.6, with alkalinity between 80 and 120 ppm. 

The ideal range for calcium is between 200 and 400 ppm. Once high calcium gets into the water, it can be hard to keep away. You can get rid of scale and control it, but in most cases it will come back pretty quickly.

Using a pool clarifier will clump together calcium for you to easily vacuum up, while avoiding cal-hypo pool shock (calcium hypochlorite) will also keep your calcium levels from spiking.

It’s also good practice to brush the walls of your pool on a regular basis. This will help prevent calcium buildup if it’s started to cling to the walls of your pool.

Additionally, there are also chemical products you can add to the pool water that can help prevent calcium scaling from becoming a nuisance.

Conclusion

Calcium scale is an issue that pool owners need to be aware of, and stay on top of, to prevent a full scale outbreak and potential damage to the pool.

By understanding the importance of maintaining a healthy pH balance and sticking to a maintenance schedule, your chances of encountering scale issues will be drastically reduced.

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