Calcium Hypochlorite: What Is It and How it is Used

Is it time to shock your swimming pool? There are various solutions to get the job done successfully, but you know you need to use calcium hypochlorite. This chemical is one of the most cost-efficient, popular strategies to shock your pool. My goal is to give you the tools and insight to learn how to use cal hypo, how it works effectively, and the optimal times to use it.

What Is Calcium Hypochlorite and How Does It Work?

Calcium hypochlorite, or cal hypo for short, will be an ingredient in a pool shock container, but it is also an effective water sanitizer itself, often used to clean drinking water too. This chemical compound has been utilized since the 19th century, and it is one of the least costly alternatives to shocking your pool.

It gets created by mixing calcium oxide (lime) with chlorine gas. The result contains a strong base, and it usually gets sold in stores as a granulated solid. It reacts well with a variety of chemical compounds, and it carries a higher pH level. One of the many reasons why it is a popular product is its availability, price, ease of use, and ability to store for long periods.

So how does calcium hypochlorite work? The component of cal hypo that disinfects your pool is the chlorine. Most commercially sold cal hypo products contain anywhere between 65% and 75% chlorine in the mixture. For every 1ppm of free chlorine (FC) in your pool, calcium hypochlorite adds about 0.8 ppm of calcium into the swimming pool water.

When the cal hypo is poured into the pool, the chlorine compounds will encounter the microbes and begin to disturb their functions. It does this by attaching to the enzymes of the microbes’ cells. Soon it will ultimately kill the bacteria by disrupting all the inner workings and destroying the cell walls. As it continues to hunt down all microbes in the water, your swimming pool will get sanitized.

It also aids in additional water treatment to minimize algae and oxidize chloramines and chemicals. A swimming pool is adequately sanitized between 1.0 and 4.0 ppm.

Calcium hypochlorite usually works most effectively at night. It contains unstabilized chlorine, which will get destroyed by sunlight. It would help if you aimed to deploy the cal hypo at dusk to wake up in the morning to a clean pool.

For more on the science of your pool, be sure to read by swimming pool chemistry 101 guide.

In The Swim Calcium Hypochlorite Chlorine Granular Pool Shock - 50 Pounds
  • NOTE: This item cannot be shipped to Alaska or Hawaii (item will be removed from your order).
  • Fast-acting Calcium Hypochlorite Cal-Chlor chlorine granules provide 68% available chlorine for hard-hitting immediate results!
  • Clears cloudy water or dull water appearance. Non-stabilized formula is ideal for super shocking or everyday use, contains no cyanuric acid.
  • Cal-Chlor granules can be used in swimming pools, spas and hot tubs. Must pre-dissolve/dilute to prevent bleaching of the liner.

When to Use Calcium Hypochlorite in Your Pool

While calcium hypochlorite can be a reactive solution to a dirty pool, you should try to keep your pool clean. You should not wait for the disgusting chloramines to build up in the pool, but you should have a maintenance schedule. It would be best for you to shock your swimming pool every week.

There are also unique events that will require you to shock your pool. If you recently experienced a bad storm in your area, debris could have been blown into the pool. Another time to shock your pool with cal hypo is after excessive use, such as a pool party. During this time, an extra amount of people brings in oils, sunscreens, bodily fluids, and other germs that will need to be eradicated immediately.

You should also shock your pool if the pool levels have changed drastically within the last week. This water level change could leave a variety of microbes behind, which will need to get addressed through a pool shock. The best thing for you to do is stay proactive and ensure that your swimming pool can combat bacteria, algae, and other harmful contaminants.

Why Calcium Hypochlorite is an Effective Solution for Your Pool

Safety should always be a priority for you and your family, and it all starts with how clean your pool is. Your swimming pool must be shocked on a consistent schedule to keep your water clean and safe for the people who use it. Not only will shocking the pool raise the sanitizer level, but it will also re-energize the existing sanitizers.

When chlorine attaches to organic matter like body oils, leaves, debris, and dead skin, these harmful chemicals are created. Chlorine cannot perform its regular job effectively when trapped inside this bond. The typical pool smell that you experience does not mean things are fine, but it means that a higher level of chloramines is floating throughout the water.

Chloramines are more than an annoying compound that makes your pool smell. They can also cause respiratory problems in humans, which is another reason why it is essential to deploy Calcium Hypochlorite consistently.

How to Shock Your Pool with Calcium Hypochlorite

Not everyone’s pool is the same, so the step-by-step process will differ depending on the type of product you use and the size of the swimming pool. Besides adhering to the usage and storing instructions on the packaging, the overall process of shocking your pool with cal hypo is simple and straightforward.

The first step is to gather the necessary set of supplies to perform the shock. This collection of items could include the cal hypo, 5-gallon bucket, safety goggles, closed-toed shoes, pants, long-sleeve shirts, chemical-resistant gloves, and a wooden stir stick. Make sure that you have put on all the necessary safety gear or have it accessible or close by.

Next, you should perform testing on your swimming pool water for TC, FC, and CC. Please ensure that you pay attention to your calcium levels if you have harder water to prevent possible hardware issues. It would help if you then calculated how much of the cal hypo you will need to add. If you did not use the math calculation, the bottle of the solution would most likely tell you how much to handle.

After you have measured out the ideal amount of solution, you can then fill up your bucket to 75% capacity with warmer water. Make sure to add the cal hypo to the water one pound at a time, and then stir at each round of dumping. Continue to stir this consistently until the sanitizer is fully dissolved in the bucket.

It is now time to walk around the pool and pour the mixture into the surrounding edges. It would help if you dispersed it evenly and slowly. If you have any leftover residue in the bucket, you can dunk it into the water, mix it around gently, and then continue to walk and pour.

I would advise you to remain outside of the pool for at least eight hours. If you go in too early, you can put yourself at risk for itchy skin, eyes, or damage to your swimsuit. If you decide to shock the pool at dusk, this should not be too hard to abide by. But to avoid any confusion for your family or neighbors, you can sign out to let people know.

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Calcium Hypochlorite vs. Sodium Hypochlorite

Make sure you know the difference between calcium hypochlorite and sodium hypochlorite (liquid bleach). While both alternatives are proven disinfectants, there are a couple of differences. Calcium hypochlorite contains calcium, and sodium hypochlorite does not have it. Areas that contain higher levels of calcium hardness might not react as well to calcium hypochlorite.

Not only is sodium hypochlorite calcium-free, but it also does have as much available chlorine. Overall, it is a much cheaper product than calcium hypochlorite. If you live in areas with higher calcium hardness levels, this might be a better option for you in the long run.

Health and Safety Considerations for Calcium Hypochlorite

Regardless of maintaining a private or public swimming pool, it is essential to keep the safety precautions in mind. You want to keep your pool safe and healthy, but you always need to protect yourself first.

If your clothes have been contaminated with calcium hypochlorite, you should change into some clean clothes. It would help if you also took the contaminated clothes straight to the laundry room and not mix with other articles of clothing. It would also be best if you had an eyewash station or something similar close by if it gets in your eye when shocking the pool.

After you are done using the cal hypo for shocking the pool, you should immediately use a wet method of vacuum to clean up the areas around the pool. There is always a small chance that small traces of cal hypo will be left on the ground. Try avoiding dry sweeping as much as possible, as the dust and debris could fall back into the water.

Final Wrap-Up

As you can see, many components go into utilizing calcium hypochlorite effectively. When you invest time understanding how it works and its potency, you can make your pool a safe, clean place to swim. It takes discipline and patience to shock your pool consistently, but your guests and family will thank you for such a beautiful place to swim!

Questions? Let me know and I’d be happy to help.

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