Which Chlorine-Alternative AOP Pool System is Right For You?

You may have heard about the pool and spa industry’s new breakthrough alternative sanitation technology called AOP (advanced oxidation process), but do you know how it works or how the two AOP methods systems differ?

Chlorine can be costly, time-consuming to maintain, and harsh on your skin, eyes and lungs. Alternative options, like AOP pool and spa sanitation, offer a healthier solution with protection beyond capabilities of chlorine, salt or bromine. 

In this guide, we explore the top AOP systems and why this new technology is changing the industry. We’ll help you decide which AOP is best for your home pool or spa.

What Are AOP Pool and Spa Systems?

AOP pool and spa systems are a cutting-edge approach to water treatment that goes beyond traditional chlorine, salt or bromine sanitizers. AOP systems make hydroxyl radicals, the most powerful oxidizers used in pool, spa and waterpark treatment. According to NASA, hydroxyl radicals act as “nature’s detergent” by helping break down pollution. These radicals make the earth’s air clean and healthier to breathe.

Since hydroxyl radicals are more powerful than chlorine, they can reduce the need for pool chlorine, salt and other chemicals. In pool or spa water, these radicals break down and destroy bacteria, pathogens and other contaminants. With less need for chlorine to combat contaminants, AOP minimizes combined chlorine (chloramines) and other disinfection by-products that cause odor, cloudy water and irritation. Therefore, AOP pool and spa systems offer a more healthy, refreshing and environmentally-friendly swimming experience. 

However, not all AOP pool and spa methods offer the same results. Because of the demand for chlorine-free or low-chlorine pools and spas, companies have come out with their own ‘AOP’ methods using various technologies. While they have the same name, there are two different types: Hydroxyl-Based AOP and ozone + UV AOP pool and spa systems.

Top 2 AOP Pool and Spa System Methods

1. Hydroxyl-Based AOP Pool & Spa Systems

Unlike other AOP pool systems, patented Hydroxyl-Based AOP uses a science-backed process inspired by the natural way hydroxyl radicals clean the air we breathe. Being patented means Hydroxyl-Based AOP is a new, unique and one-of-a-kind technology that’s legally protected from being copied on the market. It uses the latest cutting-edge AOP technology available, and is considered a more easy and sustainable approach.

Hydroxyl-Based AOP pool systems pull in surrounding air we breathe and treat it. Inside the AOP system, those oxygen molecules are split (from O2 to O1). Then, Atomic oxygen (O1) is air-injected into plumbing and creates hydroxyl radicals by a reaction to pool water. 

Using patented Hydroxyl-Based AOP to make high concentrations of hydroxyl radicals, your pool water feels like freshwater, looks crystal clear and smells odorless. It’s best fit for those with skin sensitivities, asthma and allergies. Additionally, maintaining an Hydroxyl-Based AOP system is easy, requiring only a 5-minute cartridge exchange after each year of use. Unlike ozone + UV AOP, this Hydroxyl-Based AOP system maintenance requires no special tools, professional service training or downtime. 

Hydroxyl-Based AOP Key Features:

• Uses a patented, one-of-a-kind AOP technology
• System treats air, not water 
• A dry system, with air flowing through
• Available in one form from the patent-holding manufacturer

Hydroxyl-Based AOP Pool System Pros:

• No irritation on skin, hair and eyes
• Lowest chlorine usage possible
• Water feels soft
• Clear water quality
• Easy system care that takes 5 minutes each year
• Proven to scale up to water parks
• Non-corrosive water
• Chlorine-resistant illness protection
• Healthier chlorine alternative
• Full-flow water treatment

Hydroxyl-Based AOP Pool System Cons:

• A patented technology, only manufactured by Clear Comfort
• Higher upfront cost
• Needs circulation to operate
• Needs a residual sanitizer for algae

2. Ozone + UV AOP Pool and Spa Systems

As a more common “AOP” method, ozone + UV AOP pool systems use a two-part process that makes hydroxyl radicals in a round-about fashion. Ozone and UV pool treatment technologies have been used separately for decades, but recently have been used together to make hydroxyl radicals. First the ozone + UV AOP pool system injects ozone (O3) gas into pool plumbing. Then, the ozone + UV AOP pool system passes water over a UV lamp. Water flowing through systems can cause wear-and-tear, which can lead to repairs.

Remember, while Hydroxyl-Based AOP and ozone + UV are both “AOP”, they’re two physically-different technologies. These AOPs vary in installation, maintenance time, treatment capacities and overall results. A big difference between these two AOPs is system care.

Ozone + UV AOP pool systems need maintenance for both a UV pool system and an ozone pool system, taking up to 12 hours each year. Additionally, the energy-consuming UV lamp maintenance requires gloves, special tools and professional training. 

Ozone + UV AOP Key Features:

• Uses a ozone and UV technologies
• System treats air via ozone and water via UV 
• A wet system, with water flowing through
• Available in multiple forms from different manufacturers

Ozone + UV Pool System Pros:

• No irritation on skin, hair and eyes
• Lower chlorine usage
• Water feels soft
• More affordable than other AOPs
• Chlorine-resistant illness protection
• Healthier chlorine alternative
• Full-flow water treatment

Ozone + UV Pool System Cons:

• Maintenance for both ozone and UV system parts
• Large system installs may need pipe reconfigurations
• Needs degassing for toxic, corrosive ozone gas
• Complex install, maintenance and component replacements
• Less effective in certain temperatures and pH level
• System wear-and-tear from water flow
• Needs circulation to operate
• Needs a residual sanitizer for algae

How Do These AOP Pool Systems Compare?

Comparing these two AOPs is similar to Wi-Fi and dial-up internet. While both generate hydroxyl radicals, they have different technologies, results and capacities. The biggest misconception about AOP in pool and spa treatment is easy to find online. The common myth is that “AOP” is limited to traditional ozone and UV pool or spa technologies, staples in the industry for decades. This is quickly cleared up with some research.  

Steve Goodale, a contributing writer for Aqua Magazine and creator of one of the largest pool and spa resources called Swimming Pool Steve, wrote a review of the top AOP pool systems. The AOP review included: the DEL Solar Eclipse and Prozone ECO Master ozone-UV AOP pool systems, and Clear Comfort’s hydroxyl-based AOP pool systems.

One important difference between these systems is something that is often overlooked when choosing a disinfection system – flow rate. The maximum flow rate allowed by a system makes a huge difference in the speed in which that system disinfects a pool, and the pool volume that system can properly disinfect. For example, Del AOP system can only treat up to 50 GPM, or gallons per minute, while Clear Comfort’s CCW100 system, can treat up to 90 GPM. That means that the CCW100 is able to disinfect the same amount of water almost twice as fast as the Del AOP system.

Flow rate is important because in order to adequately disinfect a pool it requires multiple turnovers per day. Turnover is the amount of time the entire body of water takes to be treated. Three to four turnovers are recommended for every 24 hours, meaning each turnover must take between six and eight hours to thoroughly disinfect a pool. At a flow rate of 50 GPM with an eight-hour turnover, the Del AOP50 system can only effectively treat a pool of 24,000 gallons. In comparison, the Clear Comfort’s CCW100 with its 90 GPM can treat a 43,200-gallon pool with the same eight-hour turnover.

Steve’s hydroxyl-based AOP review says Clear Comfort’s CCW100, “was listed in 2017 in multiple trade magazines as being one of the best new products in the pool and spa industry.”

The Future of AOP Pool & Spa Systems

Technology has improved the way we live, work – and now – how we treat pool and spa water. AOP technology is revolutionizing the pool and spa sanitation industry. Why? Because AOP lets pool and spa owners enjoy more healthy, eco-friendly and fresh-feeling water than ever before. However, like any technological development, it’s been adopted by industry leaders and influencers and is making its way to the mainstream.  

If you’re looking for the best alternative pool or spa sanitizer, it’s likely not a matter of if you’ll switch to AOP but when. However, remember to do your research, read reviews online and talk to your pool or spa professionals before deciding which AOP to go with. Your future-self will thank you!

Ready to find your perfect pool system? Download our side-by-side chlorine-alternative pool system comparison table now. »

Originally published on January 16, 2019.