During one of your routine water chemistry tests, you might find out that your pool’s calcium hardness levels are off. Your research likely led you to learn that calcium chloride is effective at returning pool water to healthy calcium levels. However, you might not know how this chemical works or how to use it.
I’m here to put your worries aside and equip you with the knowledge to single-handedly get your pool’s calcium hardness levels back on track.
Why Calcium Hardness Matters
Calcium is vital to the health of your swimming pool because it helps to balance the chemical makeup of your water. Therefore, when your swimming pool has the right calcium concentration (calcium hardness), it prevents you from spending extra money on products to keep other chemical water fluctuations in check.
Hard Water vs. Soft Water
When water is “hard,” it contains calcium and other minerals like magnesium. While you want these minerals in your pool, if the water has too much calcium, you’ll encounter issues with scale building up in the plumbing and lining of your pool. If you’re dealing with this issue, read my guide on how to remove calcium scale deposits from your pool.
That said, water that’s “soft” happens because it’s lower in minerals such as calcium. Soft water originates from places like rain and local, untreated water.
Unfortunately, too much soft water damages pools because the water clings to any calcium it encounters. As a result, metal pieces and grout in your pool may corrode.
What is Calcium Chloride and How Does it Work?
Calcium chloride is a chemical that’s effective at boosting calcium levels in pool water. As its name implies, its chemical makeup contains calcium.
If you have too little calcium in your pool and don’t apply calcium chloride, you’ll notice that grout, concrete, and any other surface the water touches that contains calcium begins to deteriorate. That’s because the water is extracting calcium wherever it can find it.
For that reason, calcium chloride is critical—it literally feeds your water the calcium it lacks.
Calcium chloride is also vital to pool health because it helps the water stay in balance. By having a healthy calcium level, combined with a proper pH, total alkalinity, and total dissolved solids, your pool will be ideal for swimming.
To be fair, calcium chloride isn’t the only way you can introduce calcium into your pool; calcium hypochlorite (cal-hypo for short) also contains the mineral.
However, cal-hypo isn’t as effective as calcium chloride because it’s easy to add too much calcium, making your pool go from having issues due to soft water to problems because of hard water.
How to Add Calcium Chloride to Your Pool
If you suspect that your pool has a calcium issue, but you haven’t tested it yet to know the level, your first step is to purchase calcium hardness test strips or a testing kit.
It’s simple to perform either of these tests following the instructions, and you’ll know the results instantly.
The ideal range for calcium in pool water is 200 – 400 parts per million (ppm).
Remember—calcium chloride is to treat pools with low calcium levels. If you discover that your pool suffers from a high calcium concentration, you’ll need to shock your pool and possibly add water or muriatic acid.
Assuming you have a case of low calcium on your hands, follow the steps below to get your pool back into shape.
Step 1: Prepare Your Pool
I understand the temptation to dump the calcium chloride in your pool straight away, but it’s vital that you first prepare your pool.
To do so, test the pH, total alkalinity, and chlorine of your water. Each of these numbers should fall within the following ranges:
pH: 7.4 – 7.6
Total alkalinity: 80 – 120 ppm
Chlorine: 1 – 3 ppm
If you own a digital tester, you shouldn’t have issues testing for these three items. However, if you buy test strips, double-check to make sure the test includes them.
Should you discover that any of these items are outside the recommended range, rest easy; they’re easy to fix by using the right products to counterbalance them.
After you balance your pool water, you’re ready to start addressing its low calcium issue.
Step 2: Calculate the Amount of Calcium Chloride
Pull out your calculator and get ready to run an equation. You’ll need to know the following items to calculate how much calcium chloride you should put in your water:
- Current calcium hardness (in ppm)
- How many gallons of water are in your pool
As a general rule, for every ten ppm of calcium your pool water needs to increase, you should add two ounces of calcium chloride per 1,000 gallons of water.
Phew, that’s a mouthful! Let me break it down for you.
Let’s say you need to increase your calcium levels by 30 ppm, and you own a 20,000-gallon pool.
That means that you’ll need to divide 30 ppm by ten ppm, which comes out to 3 ppm. Then, multiply three by two ounces (for 1,000 gallons of water), which gives you six. That’s the number for 1,000 gallons of water.
Given that you have 20,000 gallons of water, you need to multiply six by 20, which gives you 60 ounces of calcium chloride that you’ll need to add to your pool water.
Step 3: Get Your Gear Ready
With the calcium chloride calculations under your belt, the hardest part is over. However, this step is critical to ensure you stay safe during the application process.
On its own, calcium chloride isn’t a very harmful chemical. Nevertheless, when you add it to water, it becomes extremely hot—it could even burn you if you’re not careful.
For this reason, it’s critical that you wear the appropriate clothing to stay safe. You should wear a well-fitted pair of goggles, a long sleeve shirt and pants, and gloves with chemical-resistant properties.
According to a study on soft tissue necrosis, calcium carbonate rarely causes skin issues in its salt form. However, the heat released when calcium chloride mixes with water can cause calcium deposits on the skin and burns.
Step 4: Prepare the Mixture
There’s not a whole lot you need to do to get calcium chloride ready. However, you should mix the chemical with water instead of dumping it directly into your pool.
To do so, grab a five-gallon bucket and fill it about 75% of the way with water from your pool. With your calculations in hand, pour the appropriate amount of calcium carbonate in ounces into the bucket.
Make sure to pour slowly because of the hot chemical reaction the calcium carbonate will have. Furthermore, it’s best practice to never pour water on top of pre-measured calcium carbonate for your safety—always put pool water in the bucket first, followed by the chemical.
Step 5: Add the Calcium Carbonate to Your Pool
With your pool pump turned on, circle the circumference of your pool and gradually pour the calcium carbonate mixture into the water.
There are a few things to keep in mind during this time. The first is that this mixture can destroy a pool’s finish, so you should be careful to keep it from splashing up on the sides. Secondly, you should brush the sides of the walls after you pour in the substance to help move the solution around the water.
After waiting for a complete cycle, re-test your water. If the calcium hardness level is within the 200 – 400 ppm range, then you’re free to use your pool again.
And that’s about it. Any questions? Let me know.
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