Here’s How To Remove Calcium Scale From Your Pool


If you want to remove calcium scale from your swimming pool, you have a couple of different options depending on where the scale has started to form and how difficult it is to remove.

This post lays out the process for removing the scale in the simplest terms possible.

There are three primary ways to remove calcium scale:

  • 1Use muriatic acid. This is the most effective to remove scale, but also comes with some safety precaution.
  • 2Use white vinegar and a scrub brush. This method works best on calcium scale on your tile, and requires you to lower your water levels a bit first.
  • 3Use a pumice stone. This method works best on calcium scale on your plaster.

Remember: while calcium scale looks pretty harmless, it can actually cause damage to your pool in ways you can’t see right away.

So you want to get rid of it as quickly and efficiently as possible.

What you’ll need to get started

Here’s some gear you’ll want to have on hand before starting:

What is calcium scale?

Calcium scale, sometimes also called limescale, “is a hard, off-white chalky substance often found on the metallic parts of water-operated machinery.”

Calcium build-up on your tile and plaster can be a result of hard water in your area.

Scaling starts out just looking a little like white foam around the water line.

That foamy looking white stuff becomes hard as a rock and if not treated regularly, almost impossible to remove. 

Calcium scale can also start to clog your pool filter, coat your pipes, and overall just wreak some havoc on all your working parts! 

But it also starts to erode materials underneath it, like your pool tiles, fiberglass, ladders, liner and grout. 

Not only that, but it can cause some pretty nasty looking stains if left untreated, especially on vinyl. 

Types of calcium scale

There are two main types of calcium scale you should know about:

1. Calcium carbonate

Carbonate scale is the most common type of scaling, and it is primarily affected by the pool’s pH levels.

High pH levels are what “drives calcium carbonate out of solution and into scale form.” [source]

2. Calcium silicate

Calcium silicate is a little more grayish-white than calcium carbonate.

It’s also harder to get rid of and is usually caused by pH levels that are too high. [source]

How does calcium scale get in your pool?

Calcium scaling is usually caused by high calcium hardness levels, and triggered by high pH and high alkalinity. So it’s important to test the calcium hardness levels in your pool every time you test the other chemicals. You can either do this yourself with a pool test kit, or bring a water sample into a pool service store to do it for you.

But usually if this level is off, the pH level will also be off, as pH is actually the agent that affects calcium buildup the most.

The reason for this is that a high pH level will cause the calcium that is naturally in the pool water to solidify and deposit itself on pool surfaces. This is what we call scaling and it can be a pain to get off!

Calcium scale deposits can also be left behind by evaporating water. You’ll usually see this scaling right around the water line as well.

5 tips for preventing calcium scaling

Because calcium scaling is such a pain to remove, it is best to stay on top of preventing it by taking the following precautions:

  • 1Lower your pH (7.2-7.4) and alkalinity (80-90 ppm)
  • 2Use a pool clarifier to clump the calcium films together, then vacuum them away or let your filter take care of them
  • 3If you seem to be battling unusually high amounts, avoid shock with added calcium like calcium hypochlorite
  • 4Brush your pool regularly to keep calcium from building up
  • 5Vacuum your pool every time you brush it to pick up loose calcium

How to remove calcium scale

If you still find yourself on the losing end of this white scaly stuff, you will need to spend some time removing it well to prevent any damage it might cause.

The most effective chemical for removing calcium scale is muriatic acid (or dry acid), but you need to take some safety precautions when using it.

Always wear rubber gloves, goggles and clothes that cover your body well to prevent burning and skin damage from accidental contact.

If you have light scaling, you may be able to get away with using a vinegar water solution and a scrub brush. 

And if you have a ceramic tile pool, it is better to try a gentler solution like this before jumping to the acid washing.

Calcium scale on tile

To remove scaly buildup on pool tile, you need to first lower the water levels a little so that you can easily work with whatever is around the water line.

To do this, it’s usually easiest to just siphon some water out with a garden hose.

Next, try to remove a small area of buildup with white vinegar and a scrub brush. Spray the vinegar onto the area, let set for about 20 seconds and scrub with a brush.

If it comes off, this is the method you should use for the rest of your pool. If not, move on to the acid wash.

If you decide you need an acid wash, use a five-gallon bucket to mix about 3 parts water and 1 part acid. It will start to bubble and emit noxious fumes as it works its way into the scale.

You can then use something like a watering can to distribute the wash onto the surfaces with buildup, working in small sections.

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Then use whatever tool you find works best, whether it is the brush, putty knife or pumice stone or PoolStone to remove the scale as thoroughly as possible. 

Finally, if you want to hire someone to do it for you, use a local bead blasting service to have the calcium removed professionally. 

Calcium scale on plaster

To remove scale on plaster, it’s best to start with the pumice stone to see if it will do the trick, since calcium usually forms in raised crystals on the surface.

If you have trouble removing it with the stone, you can try an acid wash with it as well.

Plaster is a little bit harder to damage, so you might even be able to use a wire bristled brush for tough deposits.

Bottom line

Calcium buildup is nothing to ignore, and just like all our pool problems, it’s easier to deal with if you stay on top of it with regular cleaning.

Always try the simple natural solutions like vinegar to begin with before moving on to harsher chemicals, and always wear protective gear to keep from getting injured!

Even though calcium scaling isn’t the easiest to remove, it does come with the simplest instructions: a little spray and a lot of elbow grease.

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