How to Remove Calcium Scale from Pool (and Prevent Tips)

How To Remove Calcium Scale From Pool


It is not uncommon to find tap water with high hardness levels. Water hardness is caused by high calcium levels, which is usually found in well or borehole water. If you use such water in your pool, there is a high probability that scaling will occur, especially if pH levels rise.

Scaling is basically the formation of white crystalline particles on the pool’s waterline. That said, in this article, we will look at the types of calcium scale, what causes this scaling, how to remove, and why to remove this white precipitate.

Things you Need to Know About Calcium Scale

1. What is Calcium Scale?

Also called limescale, calcium scale is a chalky white precipitate that piles up on your pool’s equipment, walls, or at the waterline. This comes as a result of using hard water to fill up the pool and it begins as a white soap-like foam.

The foam gradually develops into solid layers that stain the pool walls and water line while also clogging filters and pipelines.

2. Types of Calcium Scale

Calcium Carbonate

Calcium carbonate is white and flaky and is the most common type of scaling. It usually arises when the water has high pH levels and is easy to remove because it reacts with muriatic acid quickly.

Calcium Silicate

Calcium silicate also forms when the water has high pH levels but it is white-grey. It usually takes a long time to build up and therefore, if you spot it on the walls, it must also be in the plumbing narrowing the size of the water channels.

Because it takes a longer time to accumulate, it forms hard layers that are very difficult to remove. These do not react with muriatic acid and therefore, you might have to hire a professional to remove them.

3. What Causes Calcium Scale?

High Calcium Levels

The primary reason is high calcium levels (more than 400 ppm). Even if you don’t have a test kit, you can know that your water supply contains such high levels if you spot white deposits on dishes, utensils, sinks, tubs, etc.

Calcium Hypochlorite Shocking

Another cause is calcium hypochlorite for shocking. Shocking utilizes chlorine from the calcium hypochlorite tablets or powder, leaving the calcium ions unused. These can accumulate slowly to raise the calcium concentration to dangerously high levels.

High pH, Alkaline and Temperature 

High pH and high alkaline levels also cause scaling but indirectly. These conditions create a conducive environment for scaling to occur because they drive calcium out of the water solution to solidify. This solidification is further quickened by high water temperature levels.  

4. Why Should I Remove Calcium Scale from Pools? 

To Prevent Clogging

Scaling clogs water pipes and filters, which slows the water circulation rate and minimizes the effectiveness of the filters. This also minimizes the amount of water passing through the pump, which might cause it to overheat.

To Prevent Cloudiness

The white or white grey calcium precipitates cause cloudiness and this interferes with visibility as you swim. It also makes the water not very pleasant to swim in.

To Prevent Staining 

Calcium scale can give you a very hard time when cleaning the residue on tiles, vinyl, and other wall surfaces. Therefore, you should remove it as quickly as possible before it leaves permanent white marks.

How to Remove Calcium Scale from Pools

Remove Calcium Scale from Pools


1. Use Muriatic Acid

Muriatic acid is very potent and this makes it ideal for removing tough scaling. However, it should be handled with care. You will need protective gear, a non-abrasive scouring pad, a plastic bucket, a plastic measuring cup, a plastic spray bottle, and a plastic spoon.

  • With your protective gear on (gloves, goggles, and respirator), prepare the cleaning solution. Put about a gallon of water in the bucket then pour in about 8 oz. of the acid. Do it in this order to minimize splashing of the acid.
  • Stir the mix using the plastic spoon then pour in some of it to the plastic spray bottle. This will minimize the chances of you getting into contact with the solution as you clean the walls.
  • Spray the acid solution to the scaling, which should react to create a foam. Leave it for about a minute then use the scouring pad to scrub the dissolved limescale.

Note: Make sure you mix the acid and water solution outside for safety purposes. Also, while scrubbing the pool, do it from the outside. Don’t get in the pool until you balance the pH levels.

2. Use White Vinegar and Scrub Brush

White vinegar is not as strong as acid. As such, it is not ideal for removing very tough scaling. Together with a scrub brush, you can use vinegar to clear light scaling on tiled walls. Simply apply the vinegar, give it a few minutes to dissolve the scale then scrub it off.

3. Use a Pumice Stone

Pumice stone has a rough texture and it works best when scrubbing scale from plaster walls. It can also be used on tiled walls but you must be careful not to scratch the surface. Though very manual, the benefit of this cleaning method is that no chemicals are used.

Tips for Preventing Calcium Scale

Tips for Preventing Calcium Scale


1. Keep tabs on the pool’s chemistry 

High pH and alkalinity create the perfect environment for scaling to occur. Keeping these factors balanced is key to preventing the formation of this white precipitate and therefore, you need to continuously test and balance the pool’s chemistry as required.

2. Use a clarifier

A clarifier is a setting tank that lets calcium particles to clump together and set. This makes it much easier for the filter to trap these particles before they cause scaling.

3. Brush Your Pool

This is important because it helps to remove the small calcium layers before they pile up to form large layers of chalk. You can also use a vacuum cleaner (manual or automatic) to help you out in this.

4. Avoid Calcium Hypochlorite Shocking

As stated above, using calcium hypochlorite leaves unused calcium in the water, which might cause scaling. The best alternative is to use non-chlorine shocks, which don’t have calcium and chlorine. Instead, these use active oxygen to sanitize the water.


In conclusion, it is important to prevent calcium scale from developing into a big problem because cleaning it out can be a big hassle.

Using the tips above will help you to keep everything in check. However, if the chalk has already developed, use either of the methods above to clean it out.