« Blog

How does AOP compare to ionizers in water sanitization?

Ionic water treatment is an option for secondary pool water sanitization. It is recognized as a sanitizer in the industry, and ionizers even provide a residual. But there are inherent drawbacks with pool water ionizers.

The NSF/ANSI Standard 50 for ionizers requires the addition of chlorine or bromine. Without chlorine/bromine, ionizers work very slowly and are incapable of oxidizing contaminants and breaking down organic compounds the way that more powerful secondary sanitizers do.

Would you drink this pool water?


Industry-related claims that ion systems allow for a “chlorine-free” pool are false. According to APSP’s fact sheet, ionizers must be used in conjunction with an EPA-registered sanitizer.

Ionizers kill bacteria and algae but do not oxidize. They’re just not capable of killing a wide spectrum of microbial organisms or neutralizing the diverse organic and inorganic materials eradicated by advanced sanitizers.

Hands down, the safest way to keep a pool properly sanitized is by including a residual level of protection.

As a matter of fact, no pool should go without a residual sanitizer. We didn’t make this up. The Water Quality and Health Council states, “only chlorine- and bromine-based sanitizers have staying power… (resulting) in continuous, efficient germ control lasting past the time of application.”




Pool ionizers are kinda neat actually. They work by releasing positively charged copper and silver ions into pool water through a process called electrolysis. Traces of these elements released by that process inhibit or destroy algae and bacteria respectively.

Having said that, ionizers work slowly at best in pool water. And the larger the pool, the longer it takes.

Silver ions act as a bacteriostat in the pool, meaning they prevent bacteria from reproducing at the DNA level. The concentration of silver ions released, however greatly slows down their efficacy as stated above.

Copper is a widely used algaecide in swimming pools and effectively controls aquatic algae growth. Nevertheless, certain bacteria including various Pseudomonas species (like “swimmers ear”) can develop resistance to copper ions.



Without proper water balance, pool ionization can lead to surface and liner discoloration and staining due to high concentrations of copper/silver ions.

Frequent water testing is required with ionic water treatment to ensure copper levels are optimum and prevent staining and discoloration.

And, as stated previously, ionizers alone are insufficient as a pool sanitizer. A residual sanitizer must also be used.



How do ionizers and AOP compare with respect to water sanitization? When you consider the oxidizing powerhouse that AOP is, there’s really no comparison.

AOP is to water sanitization as smallpox inoculation was to the Revolutionary War. Okay, maybe that’s a stretch. But, AOP is no doubt revolutionary in water sanitization. And it doesn’t stain the pool or leave any harmful byproducts and icky, buggy “leftovers.”


Related Posts

How AOP Can Keep You Safer from Crypto

How To Answer Customer Questions About AOP

Where Do Hydroxyl Radicals Come From?


CMP offers the compact DEL AOP 25 and the AOP 50, for pools up to 25,000 gallons or 50,000 gallons respectively.

Check out CMP Pool Sanitizer products to learn more.


  • This field is for validation purposes and should be left unchanged.

« Blog