How to Use Calcium Chloride on Your Pool

How to Use Calcium Chloride On Your Pool


Pool water requires a lot of attention to keep it clean and safe. Even when the water looks sparkling clear, it might still have hidden problems like low calcium hardness. However, this is a pretty easy issue to fix as you only need to add the correct dose of calcium chloride.

Calcium chloride is not always easy to deal with as it will not dissolve the same way as other dry pool chemicals such as soda ash or baking soda. Therefore, as a pool owner, you need to know how it works, how to use it, and why you need to add some to your pool water.

Why Do You Use Calcium Chloride? 

Calcium chloride (CaCl2) is vital for your swimming pool as it helps ensure calcium stability, which makes managing the chemical makeup of your pool water easier. Therefore, there will be fewer fluctuations in water chemistry, meaning you spend less time and money adding chemicals to the pool.

To ensure proper chemical balance in your pool water, you need to maintain calcium hardness between 200 and 400 ppm (parts per million). Adding calcium chloride can quickly raise the calcium hardness to the optimal level without changing alkalinity or pH.

If your pool water has low levels of magnesium or calcium, it is considered soft. In most instances, soft water results from using local water sources that are mineral deficient and from having too much rainwater in your pool.

Typical problems resulting from soft water include corrosion of metal surfaces in the pool, such as ladders and other fixtures, and pitting stone surfaces like decks or pool walls. Therefore, besides affecting pool chemistry, it will impact the pool’s overall structure.

Calcium chloride is not the only way to add calcium to your water, as you can also use calcium hypochlorite, which contains an even higher concentration of the mineral. However, calcium hypochlorite often introduces too much calcium to the water, which causes hard water problems like scaling.

How to Use Calcium Chloride 

Adding calcium chloride to your pool should not be a tedious job for you, provided you have what you need and follow the direction below.

What You Need

  • Granular/flake calcium chloride
  • Calcium hardness test kit
  • Plastic bucket
  • Stirring stick
  • Safety gear (at least goggles and gloves)
  • Measuring cup


Step 1: Test and Balance Pool Water

It is vital first to test the pool water chemistry and balance it before adding calcium chloride to the pool water. You need to test the pH and ensure it is within the 7.2 and 8.0 optimal level; alkalinity should be between 80 and 120 ppm, while the chlorine level needs to be 1 to 3 ppm.

After testing and balancing these crucial elements, the next step should be to test calcium hardness to check the actual level. If it is below 200 ppm, your water is too soft, and hence you need to increase the calcium hardness.

At this step, it is vital to make sure that you have a test kit or strips that can measure calcium hardness in water like the JNW Direct Pool and Spa Test Strips.

Step 2: Calculate How Much Calcium Chloride You Need

Now that you know the calcium hardness level in your pool water, the next step is to calculate how much calcium chloride you will need to raise it to the optimal range. Although you need to do some math here, it should be a quick and simple calculation.

You need around 1.25 pounds of calcium chloride to raise calcium hardness by 10 ppm for every 10,000 gallons of water. Therefore, if you have a 20,000-gallon swimming pool and want to increase the hardness by 20 ppm, you will need around 5 pounds of calcium chloride.

Step 3: Measure and Pre-Dissolve Calcium Chloride

Next, use a measuring cup to measure the calcium chloride you need. You should then draw water from the pool to fill up a 5-gallon plastic bucket to the three-quarters mark before adding the calcium chloride and stirring to dissolve it.

When handling calcium chloride and other pool chemicals, remember always to add the chemical to the water and not vice versa to ensure maximum safety. Also, make sure the granules or flakes dissolve in the water entirely.

Step 4: Add the Mixture to Your Pool Water

Make sure the pool’s pump system is on before pouring in the mixture. The pump will help ensure the solution distributes much faster. Also, when adding the calcium chloride mixture, ensure it does not splash on the pool’s finish as it can cause damages.

Step 5: Retest Calcium Hardness

Wait for a full water circulation cycle before you can retest the calcium levels. If it is at the optimal range, your pool chemistry should be okay now, but if not, you have to repeat the process. It is also good to retest other things like pH and alkalinity to be sure they are still okay.

Bottom Line 

Keeping the calcium level in your pool between 200 and 400 ppm contributes to maintaining the pool chemistry in balance. It minimizes pH and alkalinity fluctuations and ensures chlorine remains effective at sanitizing the water.

Therefore, you will spend less time and money adding chemicals to your pool water with proper calcium hardness. Hence, as you keep track of other things like chlorine levels, you should not forget calcium hardness.

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