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Is Ozone Better Than Chlorine?

There are a few options when it comes to pool water disinfection. Ask 100 people what works best and you’ll get 100 different answers. Is one really better than another?

Below, we discuss how chemical sanitizers like chlorine/ bromine and supplemental sanitizers work together to keep swimming pools clean and safe.


While chlorine (or bromine) is not perfect, there are very good reasons to use it in swimming pools. Ever since its bacteria-killing properties in water were discovered back in the 1900s, chlorine has been the most popular way to keep pools clean. When conditions are right, chlorine does everything we need it to do to protect swimmers.

Chlorine . . .  ✓ Sanitizes ✓ Oxidizes ✓ Kills Algae ✓ Holds a Residual

It’s worth noting, however, that chlorine is not a perfect oxidizer and can struggle to kill algae on its own. But it can technically perform all of the above.

What other option do you have that does all of the above? None, really. However, homeowner demand for chlorine alternatives–coupled with its inability to keep pools safe under adverse conditions–has pushed the industry to find a better solution.


Chlorine is inhibited by things like heavy bather load. Pathogens like Cryptosporidium (crypto) and biofilm are chlorine-resistant. Aggressive algae can cause a problem for chlorine, often requiring MORE specialized algaecides to control growth. Water gets imbalanced to the point where the residual sanitizer begins to fail.

This is when chlorine needs “an assist,” and supplemental/ secondary sanitizers come into play.

Related Posts: [Infographic] What Is Cryptosporidium?, [Video] About The Crypto Update From The CDC


The Model Aquatic Health Code (MAHC) recommends the use of secondary and supplemental sanitizers that keep working where chlorine stops. That means ozone is a powerful oxidizer in all conditions, especially where chlorine stops working. It destroys algae and biofilm.

It can kill chlorine-resistant “bugs” like crypto. And it works in high and low pH ranges where chlorine is barely active. It also “unlocks” chlorine when it becomes a chloramine, which actually makes the water more comfortable and chlorine more effective.

Supplemental sanitizers like ozone are not stand-alone systems. They are supplemental by definition, and all require a minimal residual of disinfectant. And that residual disinfectant is chlorine.

Industry experts tell us the best method to reduce chlorine demand in pools is through the use of supplemental sanitizers like Ozone, UV and AOP. Adding one can dramatically reduce the total amount of chlorine needed in the pool. Supplemental sanitizers work quickly to breakdown contaminants and in a much shorter time compared to chlorine.


More Posts

A New Leader In Recreational Water Sanitization Emerges

CMP Acquires DEL Ozone


A complete modern pool uses chlorine and an advanced sanitizer to remain clean, clear and safe.

Check out CMP Pool Sanitizer products to learn more.


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