How To Add Calcium Chloride To Your Pool (And Why You Should)



Many different chemicals are required to balance pool water, which keeps the water from becoming unsafe to swim in.

One chemical pool water requires is precise levels of calcium (referred to as calcium hardness), and this can be adjusted using calcium chloride.

If you’re unfamiliar with it, or don’t know how to add calcium chloride to your pool, this article is for you.

Why Does Calcium Hardness Matter?

Pool water needs calcium for stability. It makes managing the chemical makeup of the water easier, and means spending less money on chemicals due to a decrease in water chemistry fluctuations.

Pool water with low calcium or magnesium content is considered “soft”, and can be a result of filling the pool with a local water source, or from rainwater entering the pool after a storm.

Without proper mineral content, the water will seek out minerals wherever it can find them. This leads to corrosion of metal surfaces like your pool ladder and equipment, pitting of concrete pool walls and floor, erosion of tile grout, and etching/delamination of plaster finishes.

On the flipside, pool water with high calcium or magnesium is considered “hard”, and can also come from a local water source, as well using too much calcium-based product like calcium chloride or calcium hypochlorite.

High calcium levels cause floating scale in the water. It can also lead to calcium deposits building up at the waterline, as well as in the plumbing and pool equipment. This can completely damage your pool pump and filter, which is all the more reason to check your calcium levels regularly.

If that wasn’t bad enough, hard water can leave your skin feeling dry and irritated, may have a funky smell, and can even clog your pipes. Lowering calcium is also harder to fix as it requires dilution of your pool, or using flocculant/muriatic acid.

Why Use Calcium Chloride?

Calcium chloride is the go-to chemical product for raising the calcium level in your pool water because it has high calcium content.

This means, as long as you have no other products in the water that can cause calcium levels to rise, using calcium chloride will allow you full control over how much calcium is in the swimming pool.

Note: You may also come across a product called Calcium Hardness Increaser, which is basically calcium chloride in a fancy package with a more expensive price tag.

You will also introduce calcium to your pool as a byproduct of adding calcium hypochlorite (cal-hypo) to the water, but this is primarily a sanitizer (unstabilized chlorine) commonly used as shock treatment.

The problem with using cal-hypo as your everyday chlorine is that it adds too much calcium to the water. And when used for shocking, the chlorine burns off but the calcium stays in the water, compounding each time you do it.

How To Add Calcium Chloride To A Pool

Adding calcium chloride to your pool is very easy. You’ll need to have the following items on hand:

  • Calcium hardness test strips or a testing kit
  • A 5 gallon plastic bucket
  • A wooden stir stick
  • Safety goggles and gloves
  • A dry measuring cup
  • Flake or granular calcium chloride

Step 1. Balance Your Water

First, test your pool water and balance it properly. 

For ideal levels, you need to have your pH level between 7.4 and 7.6, total alkalinity between 80 and 120 ppm (parts per million), and chlorine between 1 and 3 ppm. As for calcium hardness, it should be between 200 and 400 ppm.

Make sure the testing kit you’re using tests for all of these levels. Some test strips or liquid test kits won’t account for calcium hardness, so double check before you purchase. Most digital testers shouldn’t have a problem picking it up.

Once you’ve balanced the water, take note of the calcium hardness level and move on to step 2.

Step 2. Do Some Math

Now that you have the calcium hardness starting point, you need to know how much calcium chloride to add to the water. 

This is based on the size of your pool, or more specifically how much water it holds.

In general, to raise it 10 ppm, add 2 ounces of calcium chloride for every 1,000 gallons of water.

For example, if your pool holds 10,000 gallons of water, and you need to raise the calcium hardness by 20 ppm, you will need 40 ounces of calcium chloride.

You can also use a pool calculator for this.

Step 3. Suit Up

Now that you have your measurements, it’s time to suit up in your protective gear. 

Calcium chloride isn’t overly dangerous, but when added to water it can get very hot. If you’re not careful, it might even burn you.

For this reason, it’s strongly advised that you wear chemically-resistant gloves and protective goggles, that way you won’t have to worry about any accidents.

Step 4. Mix It Up 

Start by dipping the bucket in your pool and filling it three-quarters full. Using the dry measuring cup, measure out the dosage of calcium chloride you figured out in step 2.

Pour the calcium chloride into the bucket of water. For safety reasons, you should never add water to chemicals, always add the chemical to water.

Mix up the solution using the wooden stir stick until the calcium chloride is fully dissolved.

If you are having problems dissolving it all, you may want to add an ounce of SC-1000, which is a chelating agent that will help things along.

Step 5. Pour It In

Walk the perimeter of the pool and pour the calcium solution in.

Ensure the pump is running so that it will be circulated throughout the pool. We’d also recommend brushing down the walls to help move the calcium chloride around.

Only add calcium chloride when the pool is full. The heat from it can damage the pool finish if you add it while the pool is still filling.

Wait one full cycle before retesting the water, and adjust the chemical levels if needed.

Even Pools Need Calcium

While we all wish our pools were gentle on our skin, there will always be some sort of harshness to contend with.

Adding calcium chloride is vital to stabilize the water, lessening the effects of pH and alkalinity fluctuations, while protecting the pool at the same time.

Categories: Pool Care, Pool Chemistry