Calcium On Pebblecrete

How To Remove Calcium From Pebblecrete Pool Surfaces

Calcium scale can be troubling to remove, and the process can be made even more complicated by the unique texture and composition of pebblecrete pools.

Luckily, removing calcium scale from your pebblecrete pool surfaces doesn’t have to be any more complicated than with other types of pools.

In this article, we will talk about how to identify calcium scale and deposits on your pool, the causes of calcium scale build up, how to remove this scaling, and ways that you can prevent calcium scale from forming on the surfaces of your pebblecrete pool in the future.

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How to Identify Calcium Scale and Deposits

Calcium scale and other related mineral deposits typically show up on the surface of your pebblecrete pool as white stains that resemble crystals or nodules.

These stains are especially common around the waterline of your pool, but can occur anywhere that comes in contact with the water.

Most white colored, resilient buildups of substances on the lining of your pebblecrete pool are caused by calcium, so these are fairly easy to properly identify.

Additionally, water cloudiness can be an early indicator that calcium stains are likely to develop, although this condition also has many other causes that would first need to be ruled out.

Causes of Calcium Scaling

Calcium scaling is caused by the dissolved mineral calcium in your pool water coming out of solution and forming a solid. This solid is typically in the form of calcium carbonate - CaCO₃.

High calcium in your water may be the result of using bore water to fill your pool, especially in areas where certain types of stone mining are common. However, overuse of chemicals like calcium hypochlorite to sanitise or shock your pool can lead to excessive calcium levels over time.

In addition, pool water that is chemically out of balance tends to produce calcium scaling faster. This is because the rate at which the calcium deposits form on surfaces can be affected by other chemical properties, such as the total alkalinity of your water.

Remember that the carbonate in calcium carbonate is a form of alkalinity, so excessive alkalinity can increase one of the ‘ingredients’ that forms calcium scale.

Water with especially high water hardness readings are more prone to develop calcium scaling. Test strips can tell you the total hardness of your pool water, which should ideally be between 200-400 parts per million (ppm).

Many pebblecrete pools are often composed of pebbles that are naturally high in calcium content, which can dissolve into the pool water (often as calcium hydroxide - Ca(OH)₂) and contribute to higher overall readings.

How to Remove Calcium Scaling

The first step you will want to take to remove calcium scaling is to rebalance the pH and total alkalinity levels of your water. When calcium scale begins to form, either the pool’s pH is too high, or the total alkalinity is too high.

You should always test these levels to be sure that adjustments are needed, and in what amounts. Ideal levels for total alkalinity in your pool should fall between 80-120 ppm, with a pH level reading between 7.2-7.6.

Levels that are reading higher than these should be treated with a pH decreaser containing either sodium bisulphate or hydrochloric acid.

Next, you will need to use a scale removing product. There are different options available for this, but we recommend a stain remover that is added to your pool’s water.

Our favourite one for calcium scale is the Serious Stain Remover, which is formulated with pebblecrete pools in mind to reduce the need for scrubbing. Simply add 1.25kg per 25,000L of pool water and leave the solution to stand in your pool for 2-3 days.

The effects of this stain remover can also be further strengthened by creating an abnormally low pH in the pool water before use.

To remove calcium scaling, you will also want to remove any high amounts of dissolved calcium in your water. However, since many stain removal products contain agents that work to remove these minerals in their dissolved form already, we have opted to include this step in our preventative section instead.

How to Prevent Calcium Deposits in the Future

After treating your pool for calcium scale, you will want to test the total hardness of your pool water, as well as the water that you source your pool with. If your calcium levels are high in either, you will need to look at reducing calcium hardness in your water.

Left unattended, these high levels of dissolved calcium will lead to scale buildup.

If your pool is reading above 400 ppm after the scale removal process, you will want to use a calcium hardness remover. This treatment solution binds to calcium in your pool in order to remove it from the water, which prevents it from forming deposits on the surfaces of your pool.

It’s also worth testing the calcium concentration of your pool fill water.

If you have naturally high amounts of calcium in your pool’s source water, it is important that you use a calcium hardness remover, or another stain prevention agent, whenever you fill up your pool in order to prevent future scale buildup.

If your fill water is naturally low in calcium, the excess calcium may be coming from other pool chemicals that you are using. Take a look at the chemicals that you add to your pool regularly, and try to substitute the calcium containing ones with others if possible.

It also means that draining and refilling some of your pool water can be a viable way to lower calcium levels if you prefer that to the calcium hardness removers.

Use this pool calcium calculator to work out how much water needs to be drained and refilled.


Calcium scaling can be a common problem in pebblecrete pools, especially if you source your pool with water that is naturally high in calcium. Fortunately, removing calcium scale from pebblecrete pools is not as daunting of a task as it may seem at first.

That being said, it is important to remember that prevention is always the best approach to avoiding calcium scaling or any other types of stains.

If you find that the calcium has taken over your pool and there is no way to remove it, you can look into resurfacing your pool instead. Here's a list of our recommended pebblecrete resurfacers in Brisbane, along with our cost calculator to help you get a budget estimate.

Do you have any questions about how to remove calcium scaling from pebblecrete pool surfaces? Let us know in the comment section, we’d love to help!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.