UV vs Hydroxyl-Based AOP Pool Disinfection: A Comparison for Aquatics Professionals

For the past 30 years, ultraviolet light disinfection has been the go to secondary disinfectant product for commercial pools. The industry has marketed UV systems as economical and eco friendly and has accepted that they decrease the amount of primary disinfectant required. In addition, UV systems have been hailed to be safe.

In 2014, Clear Comfort released the first direct hydroxyl-based advanced oxidation product to hit the commercial pool industry. The Clear Comfort system produces highly oxidative hydroxyl radicals directly from ambient oxygen that sanitize the water quickly and effectively kill waterborne pathogens on contact.

To assist aquatics professionals and commercial pool service professionals in understanding the differences between UV and hydroxyl-based advanced oxidation, in the discussion below I provide a comparison of the technologies.

Increased chlorine consumption?

While many UV disinfection products claim to reduce the amount of needed chlorine, studies show that UV increases the rate of free chlorine consumption (Blatchley, 2012). This means that UV pools require more chlorine than pools that solely use chlorine.

In contrast, the hydroxyl radicals that the Clear Comfort system produces oxidize organic matter in the pool piping more quickly than chlorine. Hydroxyls allow free chlorine to be more effective at breaking down the remaining organic matter and thus less chlorine is required. Many commercial Clear Comfort customers have been able to cut their chlorine consumption by up to 70 percent. See the case study.

Proven pathogen reduction?

Although chlorine works well on most recreational water pathogens, it falls short and secondary solutions are needed. UV is a light-driven process and does not oxidize contaminants in the water. Instead, UV denatures the microorganism’s DNA, keeping its cell membrane intact.

The highly reactive and broad spectrum hydroxyl radicals are the differentiating factor that lead to the Clear Comfort system’s proven ability to kill and destroy organisms. A University of Colorado, Boulder study proves that Clear Comfort’s technology produces a 4-log inactivation of common waterborne pathogens. Although UV systems are known to inactivate water pathogens, the Clear Comfort system has been shown kill 99.9 percent of the chlorine resistant protozoan Cryptosporidium pavum (Linden, 2014).

Formation of disinfection byproducts?

Disinfection byproducts are formed from the molecular interaction of free chlorine and organic matter, such as hair, skin, lotion and urine that enter the pool.  Exposure to these disinfection byproducts actively harms pool staff and patrons, and they are known to cause asthma, other respiratory ailments, and have even been linked to certain forms of cancer (Blatchley, 2007). Studies illustrate that UV both promotes the formation and destruction of disinfection byproducts (Blatchley, 2012).

In contrast, Clear Comfort reduces disinfection byproducts. In a case study at a YMCA pool, the Clear Comfort system removed 91.5 percent of the total haloacetic acids, 84.8 percent of  the trihalomethanes, and 68.9 percent of the chloroform — all harmful disinfection byproducts.

The true costs of UV pool disinfection

The true cost of a UV system includes an expensive installation, required professional maintenance, and a high energy demand. Buildup of biofilms, particulate matter in the water, flow rate variation and diminished bulb efficacy (even in six months) impact the efficacy of UV. Thus, the turbidity of the water needs to be kept low, the flow rate maintained in a tight range, and the lights have to be cleaned and replaced frequently (Water, Sanitation, and World Health Organization, 2006). A typical 165,000 gallon pool would require a 6,200 watt UV system which would cost $5,400 per year just to power (assuming energy costs assuming $0.10/kWh).

Clear Comfort removes the upfront cost of installation by offering a 90-day-money-back-guarantee rental-based service. The only maintenance required of the Clear Comfort system is an annual cartridge replacement which is covered in the cost of the rental. A Clear Comfort system requires 40 watts to operate which translates to $300/year in energy costs (again assuming $0.10/kWh) . The comparative case study below breaks down the total cost of ownership for a UV vs. a Clear Comfort system and extrapolates the cost over five years.

Download the UV vs. Clear Comfort  Total Cost of Ownership case study.

The bottom line matters

UV systems are more expensive to purchase, maintain, and operate than Clear Comfort systems; Clear Comfort systems are safer for your patrons, better at eliminating disinfection byproducts, require less chlorine, and kill waterborne pathogens. Take the next step to a cleaner, clear pool and help to revolutionize the pool and spa industry by replacing your UV system with Clear Comfort.  

Contact Us:

Fill out the form below to learn more about Clear Comfort’s commercial systems.


[accordion autoclose=false clicktoclose=true][accordion-item title="References +"]

• Blatchley, Ernest and Li, Jing. "Volatile disinfection byproduct formation resulting from chlorination of organic-nitrogen precursors in swimming pools."Environmental science & technology 41.19 (2007): 6732-6739.
• Blatchley, Ernest;  Li, Jing; and Weng, ShihChi. "Effects of UV 254 irradiation on residual chlorine and DBPs in chlorination of model organic-N precursors in swimming pools." water research 46.8 (2012): 2674-2682.
• Linden, Karl and Rosenblum, James.  “Measurement of Inactivation of Cryptosporidium parvum and Bacillus subtilis Spores using the Clear Comfort System.”  Karl Linden Research Group, University of Colorado Boulder. (May 15, 2014)
• Water, Sanitation, and World Health Organization. "Guidelines for safe recreational water environments. Volume 2, Swimming pools and similar environments." (2006).

[/accordion-item] [/accordion]