What is an AOP Pool System? How They Work, Pros/Cons & More

Written by Michael Dean
May 22, 2024

AOP pool system

Have you ever felt a stinging sensation in your eyes or on your skin after getting out of a chlorine pool? For years, chlorine has been the go-to choice for pool owners. While traditional chlorine sanitization is effective, it can irritate the skin and eyes of swimmers and requires regular maintenance. That’s where alternative sanitation methods such as AOP pool systems come into play.

AOP technology takes pool water treatment to a whole new level, offering a powerful and advanced approach to water sanitization. In this article, I’ll dive deep into AOP pool systems, explaining the science behind their operation and highlighting their advantages and potential drawbacks.

Main Takeaways

  • AOP pool systems are a method of water sanitization utilizing oxidation processes to eliminate contaminants effectively.
  • AOP systems can oxidize both organic and inorganic debris, combined chlorine, and pathogens.
  • AOP systems reduce reliance on chlorine, minimizing chemical odors and irritations.
  • Unfortunately, AOP systems cost more upfront than traditional chlorine sanitizing methods and may be difficult to install.

What is an AOP Pool System?

AOP pool and spa systems, also known as Advanced Oxidation Process, is an alternative method of treating water. While chlorine and salt systems reign supreme as the primary way to clean pool water, Advanced Oxidation Process systems are a popular option that allows you to reduce the amount of chlorine in your pool.

AOP systems produce a chemical called hydroxyl radicals. Hydroxyl radicals are highly potent oxidants that essentially attack and break down the cells of bacteria and other organic matter, turning them into harmless compounds. 

Think about it this way; if there is dirt, algae, bacteria, or other debris in your pool water, the AOP system gets rid of them by attacking the cells with hydroxyl radicals and neutralizing them.

These chemical treatment processes introduce highly reactive hydroxyls into the pool or spa water, eliminating unwanted contaminants.

AOP systems can even break down combined chlorine (chloramines) and pathogens. So, the sanitation process of AOP systems allows pool owners to significantly reduce their usage of traditional chemicals like chlorine and bromine.

Notice that I said to reduce usage and not completely stop using chlorine. While AOP systems are a great way to reduce the chemical levels in your pool, you still need some chlorine or bromine to keep the pool properly sanitized.

How AOP Pool Systems Work

As I mentioned, AOP pool systems treat water by oxidizing the debris in the water using hydroxyl radicals. There are a few different methods used to generate hydroxyl radicals in AOP systems. Let’s go over and learn about each of them for a better view of how these fascinating systems work.


In this system, ozone, generated using UV ozone generators or corona discharge, is injected into the water. This highly reactive gas then oxidizes contaminants upon contact. Essentially, the generator sends out a high-voltage burst that allows ozone to form to clean the water.

Ultraviolet Light

Another type of AOP system utilizes UV light to disinfect water. When microorganisms or waterborne pathogens come into contact with UV light, their DNA is disabled. In other words, these once-dangerous contaminants are rendered harmless and unable to reproduce. You can read my entire article on how UV pool sanitizers work for more information on this method.

Ozone & UV Combination Systems

This is likely the most common type of AOP pool and spa system. The ozone-UV combination system does just what it sounds like it does: it combines the ozone and UV light methods. These systems work by dissolving ozone gas into water, then passing through a chamber containing a germicidal UV lamp. The ozone and UV combination triggers a chemical reaction that produces hydroxyls, which, in turn, removes those nasty contaminants in the water.

This combined system covers all the bases regarding sanitization, so it is super effective. Here’s a diagram I drew up showing how these systems work.

AOP pool system


  1. Ozone and UV combo system
  2. Air check valve
  3. Tubing
  4. Venturi
  5. Manifold
  6. Heater
  7. Filter
  8. Pump
  9. Pool

The flow of water goes from your swimming pool at the bottom of the diagram up through the pump filter, AOP system, and back to your pool.

Hydroxyl-Based Injection

A newer AOP technology involves treating the oxygen in the air surrounding the system to create monatomic oxygen. This single-atom oxygen molecule is then injected into the water through tubes, which produces a large concentration of hydroxyl radicals within the pool plumbing. Finally, these hydroxyl radicals do their job of rapidly oxidizing unwanted contaminants.

Do You Still Need Chlorine With An AOP Pool System?

So, there is the science behind AOP systems, but do you still need chlorine if you use advanced oxidization processes to clean your pool?

The short answer is yes. Unfortunately, AOP systems don’t sanitize your water to the point of eliminating chlorine entirely.

While AOP systems are highly effective in oxidizing contaminants and providing excellent water quality, you’ll still need a traditional chemical sanitizer to ensure your pool is safe to swim in. This is because AOP technologies produce a fixed amount of hydroxyl radicals that can address only a certain level of contamination.

AOP systems alone cannot treat a pool with dangerous microorganisms, such as cryptosporidium, giardia, or E. coli. After all, no matter how well you treat your pool, accidents happen. You may host a neighborhood pool party, only for one of the children to go potty in the inviting pool. And did you know that 1 in 5 adults urinate in swimming pools? Yuck! In these situations, an AOP system by itself may not be able to handle the extra dirty water.

While AOP can help destroy these unwanted organisms, it should be used alongside a powerful and reliable sanitizer such as chlorine or bromine.

You must maintain a chlorine concentration of 0.5 to 1 parts per million (ppm). In comparison, you’ll need 1-3 ppm of chlorine in a traditional chlorine pool.

Pros And Cons of Using an AOP Pool System

There are many pros and cons to using an AOP system. Let’s review them.


  • Clean water: AOP systems oxidize contaminants, combined chloramines, and pathogens. This makes your pool cleaner, clearer, and safer for swimmers.
  • Reduced chlorine usage: AOP systems take on some of the sanitizing burdens of chlorine, allowing you to use less chlorine in the pool. Fewer chemicals = happier swimmers!
  • Fewer maintenance requirements: Maintenance requirements can be relatively low depending on the type of AOP system. Hydroxyl-based AOP systems, for example, may only require a replacement aluminum cartridge once per year.
  • Less irritating than chlorine: AOP systems appeal to individuals with sensitivities or allergies to chlorine, as the lower levels make the water less irritating.


  • Initial cost: AOP systems typically cost more upfront than traditional sanitization methods.
  • Installation: Certain types of AOP systems, such as ozone-UV combination systems, can be complex to install and may require professional assistance. The need for electrical connections can add to the difficulty of the installation process.
  • Additional equipment needed: AOP systems may require additional equipment, such as UV lamps or ozone generators.
  • Limitations: While AOP systems are effective, they cannot easily handle sudden increases in bather load or contamination.
  • Chlorine dependency: AOP systems still require a certain amount of chlorine for ongoing protection against future contamination.

How Much Do AOP Pool Systems Cost?

The cost of AOP (Advanced Oxidation Process) systems can vary based on a few different factors, including the size of your pool and the specific technology and features you choose. 

On average, a quality AOP system for a typical inground pool falls within $700 to $1,900 without installation costs.

While this is definitely a hefty initial investment, the long-term advantages and benefits of AOP systems make them a wise and cost-effective choice in the long run.

Popular AOP Pool System Brands

When considering an AOP system for your pool, you should get familiar with some of the leading brands in the market. These brands have established themselves as reliable providers of AOP technology. And you want nothing but the best for your pool! Here are a couple of the popular AOP system brands worth exploring.

Clear Comfort

Clear Comfort is a well-known brand that specializes in hydroxyl-based AOP systems. Their patented technology uses hydroxyl radicals to sanitize the pool water. Clear Comfort systems are known for their simplicity, ease of installation, and low maintenance requirements.

DEL Ozone

DEL Ozone is a reputable brand recognized for its ozone-based AOP systems. Their ozone generators inject ozone gas into the water, eliminating contaminants and improving water quality. DEL Ozone systems are known for their durability, efficiency, and ability to reduce chlorine/bromine usage.

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Bottom Line

AOP systems ensure clearer, fresher, and safer pool water. And since there is a reduced demand for chlorine when you use an AOP system, you can enjoy your swimming pool without the chlorine irritating your eyes or skin! However, on the flip side, AOP systems typically cost more and have some limitations.

Have more questions about this complex pool sanitation process? Don’t hesitate to reach out!

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