Nov 2, 2017 10:25:53 AM / by Claude Kershner IV

A pool technician arrives at your property to perform routine service—weekly pool cleaning for residences, and service three to five times a week for commercial properties. You see the pool cleaner take various measurements and then add some liquids and powder chemicals to the pool water. You might be wondering, “What is that stuff?” “Are those chemicals safe?” “How long should I wait to swim after the pool cleaner leaves?”

These are questions that our Certified Pool Operators (CPO) get often when they’re in the field servicing pools and spas. Ultimately, people want to know: Is my pool water safe? And, more specifically, some families are concerned about the health of babies, young children, pets or individuals with skin conditions that could be aggravated by chemicals.

We think these are important questions to ask your pool professional. As a wise consumer, it’s good to know exactly what is in your pool water—you need the truth.

The good news: When a trained, experienced CPO is cleaning your pool on a routine basis (as determined by the pool’s use and typical bather load), the water is safe for swimming. Pool water is healthy, well-balanced, clean and comfortable.

Let’s get more specific now and answer the question concerning what chemicals we add to pool water, what they do, and what other pool water safety concerns you should know about.

Pool Chemistry 101: What Chemicals Go Into Your Pool—And Why

Healthy pool water is balanced with a pH of 7.4—and this pH along with chlorine levels should preferably be tested on a daily basis before the first swim of the day in commercial pools, and at least weekly in residential pools. pH can fluctuate because of rain water, the biggest factor, and from dirt and debris entering into the pool. Bather load (the number of swimmers at one time) also impacts pool water pH and can cause it to become more acidic or alkaline. It’s critical to bring pool water back into balance so it is safe and sanitary.


The basic pool chemicals that create perfectly balanced water are: chlorine, muriatic acid, sodium bicarbonate, calcium, stabilizer and Diatomaceous Earth (DE) powder for DE filters. (Filters with cartridges can be removed and washed out, while DE filters require backwashing and applying a new coating of DE powder to catch microorganisms.)

Chlorine: Chlorine is what sanitizes the pool and gives it a blue, clear appearance. Chlorine kills bacteria, thereby disinfecting the pool and providing a safe environment for swimming. Without chlorine, your pool would get cloudy and become a cesspool that harbors bacteria and disease. We’re not kidding—imagine a bathtub with 10 people in it. You probably wouldn’t want to test that water, let alone swim in it. Chlorine is absolutely essential for creating a safe, sanitary pool. Some pools have saltwater chlorine generators that produce chlorine, and those should be monitored carefully in case more chlorine needs to be added to water. Chlorine tabs are also available, and these release chlorine gradually and are dispensed through feeder systems.

Muriatic Acid: Following a pH test, we may learn that the pool water is acidic. If this is the case, we add muriatic acid to bring the pool water back into balance. Muriatic acid is safe. When the pool water pH is higher—above 7.6—you may notice the water becoming cloudy. Muriatic acid brings the pH to the proper level, thereby clearing up the water so it is not only safe but appealing for swimming.

Sodium Bicarbonate: When water is alkaline, or has a low pH, sodium bicarbonate can raise the pH level. Is sodium bicarbonate safe? Absolutely. It’s baking soda, a natural substance we use for green cleaning and baking. The form we use for pools works hard to maintain balanced pool water.

Calcium: Calcium helps protect the pool shell by filling in hairline cracks, and it gives a balanced pool water that sparkle that is so inviting that swimmers can’t help but wade in. Calcium is a completely safe chemical that works to benefit the pool structure and create an appealing environment that’s perfectly safe for babies, children, pets and adults of all ages.

Stabilizer: We add stabilizer to pool water to help hold chlorine into the pool. Cyanuric acid (CYA) prevents the sun’s UV rays from degrading chlorine—and in sunny South Florida, CYA is essential for maintaining safe, balanced pool water. Stabilized chlorine products like chlorine tabs that are gradually dispensed through a system do not require adding more CYA.

Safe to Swim: Creating The Perfect Balance in Pool Water

Balanced pool water with the correct pH is safe for babies that are three months and older to swim in. (Doctors often recommend waiting until that age.) Pool water chemicals are safe for children and pets. If you have a skin condition, consult with your doctor to find out if swimming is safe. For example, physicians will advise those with wounds to stay out of the pool—not only for the health of the person, but because open wounds can spread bacteria. (By the way, the chemicals in pool water will kill that bacteria, which is why you want to be sure that chemicals are properly applied and balanced.)

Pool chemicals are safe because they work in harmony to create water that is sanitized, disinfected, the correct pH and simply comfortable for swimming.

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How Long After Pool Cleaning Should You Wait Before Swimming?

On residential properties where a CPO pool cleaner is visiting weekly to perform service, you should wait one hour after cleaning before swimming. This allows the pool water to completely turn over through the filter. As for commercial pools, many include automatic chemical feeder systems that gradually release chemicals to ensure the proper water pH and chemical balance. With these feeder systems in place, you can swim at any time, including immediately after cleaning.

Who Do You Trust To Maintain Your Pool Water Quality?

When pool water is not properly balanced, that’s when you run into issues like bacteria growth, the presence of microorganisms, and other “nasties” that can actually make you sick. Disease can be transmitted through dirty pool water—and that’s why chlorine and the pool chemicals we described here are absolutely critical for maintaining the health and safety of swimmers.

Pool chemicals are the “good guys” that keep water sanitary, bacteria-free and safe. So, if you are concerned about adding chemicals to your pool, rest assured they are not only safe—pool chemicals are essential. You just wouldn’t (and shouldn’t!) swim in a pool without them.

This brings to mind the importance of hiring a professional to apply pool chemicals—a technician that is CPO certified, which requires many hours of certification training before gaining licensure. CPOs are well-versed in pool chemicals and understand how to create that perfect balance. Commercial pools should not be cleaned by anyone but a CPO, and we feel the same way about residential pools. Would you want an under-trained person to be in charge of adding chemicals to your pool? (We didn’t think so.)

Reef Tropical provides comprehensive pool and spa maintenance that not only saves you time, but ensures that your pool and spa is sanitized correctly, that equipment is cared for properly and that any costly issues are caught early. We take pride in our highly knowledgeable team of certified professionals that maintain luxury pools in South Florida and The Keys.

Let’s make sure your pool water is safe, sanitary and balanced. Call us any time at 305.367.2005, or fill out this simple contact form and we’ll get in touch with you.

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Topics: Pool & Spa Maintenance

Claude Kershner IV

Written by Claude Kershner IV

President Reef Tropical • Pool & Landscape

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