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Ozone Use in Hot Tubs, Spas, Swimming Pools

Guide to hot tub, spa, pool water ozone treatment

POST a QUESTION or COMMENT about how to maintain safe water quality in hot tubs, whirlpool bath tubs, spas, jacuzzis & swimming pools

Hot tub & spa or whirlpool bath chemical & water treatment using ozone generators:

Here we provide a simple table showing how to use chlorine or bromine and other chemicals & treatments to maintain a hot tub or spa, We explain how to use simple test strips to test the level of chlorine, bromine, pH, alkalinity, hardness and other spa or hot tub water properties in order to maintain a safe, sanitary hot tub or spa.

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Use of Ozone as an Oxidizer in Hot Tubs, Spas & Swimming Pools

Freije explains that because their design, use, and water maintenance are different, spas and hot tubs do not function the same nor necessariily present the same hazards as found at public swimming pools.

Illustration: the Pacifica Spa Series XL-30 Ozone Generator from AquaSunOzone, cited in detail below in this article.

[Click to enlarge any image]

Spas and hot tubs are not the same as whirlpool baths. Spas and hot tubs are used for recreation rather than for bathing. Many private spas are located outdoors. They are not drained after each use.

Most have heaters. The water is treated and filtered.... Spas, hot tubs, and whirlpool bathtubs can provide a fertile breeding ground for many microbes, including organisms that cause disease... - Freije (2000)

The use of ozone (O3) has been promoted by some spa, hot tub and swimming pool equipment & supply producers or vendors as an oxidant or oxidizing agent useful to improve water quality by removing " non-living bather waste such as body oils, cosmetics, sun tan lotions, perspiration, urine" and indeed earlier research (Bataller 2000) suggested that ozone might be a useful component of swimming pool water treatment, and as recently as 2013 (Fernández-Luna) authors have suggested that ozone treatments may reduce swimmer exposure to products of other disinfectants used in swimming pool water.

In the pool and spa water, chlorine acts as a primary disinfectant and it provides the safety residual. Ozone is the primary oxidizer. ... When Ozone is used as an oxidizer in pool and spa water, the quality of the water will improve as problems with combined chlorine compounds are eliminated and eye and skin irritations are greatly reduced.

Overall water maintenance and care are minimized as filter runs are longer since clogging greases and oils are broken down, scumline or bathtub rings are kept away or are easily brushed off. The cost of running the pool and spa is lowered as the use of the following specialty chemicals can be reduced: “shock” treatments, scumline cleaners, filter degreasers, clarifiers, scale inhibitors, scents, filter aids. (Kon, Ultra Pure, un-dated)

Is Ozone all I need to sanitize and keep my spa water clean? The quick answer is “no” but you can eliminate much of your customary sanitizer and shock with a properly functioning ozonator. ... Most hot tubs built in the last 10 years have a built-in ozone generator or are set up so you can add one easily.

So, what is ozone and why is it the best thing for sanitizing your hot tub?... Spa ozone is the most powerful oxidizer and disinfectant that can be safely used in spas. It kills all known bacteria, viruses, yeasts and a lot of other things you don’t want to know about... Your spa ozonator needs to be replaced every 18-24 months. (Cunningham, Olympic Hot Tub Blog, 2012)

Really?

Perhaps not. The ozone-promotion text above, excerpted from some hot tub and spa suppliers selling ozone generation equipment includes errors and is confusing because sometimes this marketing text even contradicts itself, suggesting that ozone is a sufficient disinfectant methods for hot tubs, spas, pools (it is not), at the same time as indicating that ozone is not "all I need to keep my spa water clean".

Indeed ozone has been used in Europe as a component in water treatment in some public swimming pools. But where used in public pools in Europe the effective use of ozone treatment system for swimming water required extensive additional equipment, steps, and monitoring, such as compressors, dryers, contact chambers and deozonators for treating vent gases and for treating ozone–containing water before returning it to the pool (Wojtowicz 2001 citing Eichelsdorfer 1982, Kurzman 1982).

Watch out: Elliot (1989) demonstrated that typically ozone treatment produced by UV radiation was not an effective spa or hot tub or pool disinfection method.

It is concluded that insufficient dissolved ozone is present for a sufficient reaction time to effect disinfection of these organisms by ozone generated by UV radiation. - Elliot (1989)

Wojtowicz (2001) who has written at length about hot tub, spa and swimming pool water disinfection and treatment has found that in general ozone is ineffective for this application and that in any event it should not be used by methods that might expose the hot tub, spa, or pool users to elevated levels of ozone. That author also found that other claims of the benefits of ozone use in hot tubs and spas were not substantiated.

Ozonating the water while the spa is in use is not recommended because the unabsorbed ozone in the ozonator vent gas can amount to 60 ppm. - (Wojtowicz 2001 p. 147)

A number of UV ozonators have been evaluated and found to be unsuitable for pool or spa use. Although UV ozonator manufacturers typically claim lower chlorine consumption (typically 60 to 90%) and the ability to operate pools and spas at lower chlorine concentrations, no independent data are provided to support these claims. (Wojtowicz 2001)

Papadopoulou notes that even where potentially effective ozone treatment equipment is installed, its maintenance has been poor and various authors reported that some important pathogens are resistant to the ozone treatment. Rigas, adding poor process design as well, noted the same maintenance problems a bit earlier (Rigas 1998).

The swimming pool with the poorest microbiological quality (THC 500 cfu/ml in 12.1% of the samples, P. aeruginosa counts 1500 cfu/100 ml in 6% of the samples) and the highest prevalence of multi-resistant isolates (73.6%) was the hydrotherapy pool - Papadopoulou(2008)

Resistance to chlorine dioxide and ozone for M. avium was 100- and 50-fold greater ... (Lumb 2004)

Zwiener (2007) offers further details about potential hazards of some swmming pool, hot tub, or spa disinfection methods. But those authors do not suggest ozone as an alternative.

... disinfection byproducts (DBPs), such as trihalomethanes (THMs), which are regulated carcinogenic DBPs in drinking water that have been detected in the blood and breath of swimmers and of nonswimmers at indoor pools.

Separately at OZONE HAZARDS readers will find a series of articles about both successful and un-successful, even dangerous applications of ozone. Also see OZONE GAS EXPOSURE EFFECTS.

Research / References: Ozone use in Spas, Hot Tubs, Pools

OZONE REFERENCES & OZONE GENERATOR INSTRUCTIONS
OZONE EXPOSURE STANDARDS
OZONE for WATER DISINFECTION
A2Z Ozone Generators, A2Z Ozone Inc. Address: 1844 Cargo Court Louisville Kentucky 40299 USA Phone: 502-499-4977 https://www.a2zozone.com/products/aquatic2
Website excerpt: The Aquatic 2 Spa Ozone Generator is designed to decrease reliance on harmful chemicals in spas up to 132 gallons or 500 liters. The Aquatic 2 is maintenance free and helps maintain crystal clear water in your hot tub without the need for additional skin irritating chemicals.
The unit produces 300 mg/hour of ozone gas that is introduced to the spa water through suction created by the spa injector, creating a vacuum like suction that pulls the ozone out of the unit and into your spa’s water.
ANSI/NSPI–4 1999 Standard for Aboveground/ Onground Residential Swimming Pools
ANSI/NSPI–5 1995 Standard for Residential Inground Swimming Pools

Aqua Sun XL-30 Ozone Generator / Pacifica Spa Series XL-30 from AquaSunOzone, now owned by CMP Products, cited below, a provider of Spa Sanitizers, Tel: 760.320.8500 Website: http://aquasunozone.com/ Email: info@AquaSunOzone.com - Illustrated at the top of this page.
AquaSun also produces the ASO3 Aqua Sun BO3, fodrmerly the XL-30 Spa Ozone Generator distributed by spa and pool suppliers and plumbing suppliers and also sold online.
And the XL80 Ozone Generator (Sundance Spas CD Aqua) - note the various names for what's essentially the same product.2019/08/18. - Internal View of this Ozone Generator is shown just above.
Illustration below adapted from an original at heaterandspaparts.com.au retrieved 2018/08/18 https://heaterandspaparts.com.au/products/xl-80-ozone-generator-aka-sundance-spas-cd-aqua

Bataller, M., Veliz, E., Perez-Rey, R., Fernandez, L.A., Gutierrez, M. and Márquez, A., 2000. Ozone swimming pool water treatment under tropical conditions. Ozone: science & engineering, 22(6), pp.677-682.
Abstract:
This paper presents the first year operation report of an ozone swimming pool water treatment system under the severe conditions of tropical climate. The system installed in a 70 m3 pool with upflow hydraulics, comprises sand filtration and ozone/bromide ion treatment.
Cupric sulfate was chosen as algaecide and pH was kept between 7.5 and 7.8 by adding adequate amounts of HC1. When required, a slight flocculation (aluminum sulfate, 5 mg/L) was applied weekly.
Water physicochemical analyses performed twice a week throughout the year, including microbiological tests, clearly demonstrated the remarkable efficiency of the treatment, fulfilling all water quality standards, even at high bather loads and during the summer months (at water temperature higher than 31[ddot]C and an intense sunlight) being economically feasible as well.
This experience will allow the extension of ozone water treatment to larger swimming pools in similar circumstances.
CMP DEL OZONE 25/50/100 INSTALLATION INSTRUCTIONS & PRODUCT MANUAL [PDF] CMP, LLC 36 HERRING ROAD, NEWNAN, GA 30265 USA Tel: 800.733.9060 ret. 2019/08/10 original source: https://www.c-m-p.com/wp-content/uploads/2018/05/DEL-Ozone-25\_50\_100-Manual-1.pdf Web: https://www.c-m-p.com
Cunningham, Alice, "The Secret to Easy Hot Tub Water Care: Ozone" [Web article], Olympic Hot Tub Pools, 12818 Gateway Drive Seattle, WA 98168-3311, (2012), Tel: 206 286-0700, Website: http://www.olympichottub.com, retrieved 2016/03/22, original source: http://www.olympichottub.com/hot-tubs-sauna-blog/2012/04/the-secret-to-easy-hot-tub-water-care-ozone/
Eichelsdorfer, D. and J. Jandik, “Long Contact Time Ozonation for Swimming Pool Water Treatment”, Ozone Science and Engineering 7(2)(1985):93-106
Eichelsdorfer, D., “Use of Ozone for Treatment of Swimming Pool Water”, in Ozone Treatment of Waters for Swimming Pools, R. Rice, Ed., International Ozone Association, Norwalk, CT, 1982, pp. 82 and 91.
Elliott Whitby, G. "The treatment of spa water with ozone produced by UV light." (1989): 313-324.
Abstract:
Some North American manufacturers are selling devices which produce ozone from UV radiation, which is pumped or sucked into spas, presumably to disinfect the water, without having to use chlorine. To test this claim, a private spa used by two people at least once a day was equipped with a UV radiation unit and an ozone (generating by UV) unit.
Bacterial analyses were conducted during experiments carried out using chlorine alone, ozone generated by UV radiation, unit and an ozone (generating by UV) unit. Bacterial analyses were conducted during experiments carried out using chlorine alone, ozone generaed by UV radiation, and ozoen in combination with UV radiation.
Heterotrophic plate counts, and counts of Staphyiococcus aureus and Pseudomonas aeruginosa were lowest when using chlorine, next lowest when using ozone #x002B; UV radiation, and highest when using UV-generated ozone.
It is concluded that insufficient dissolved ozone is present for a sufficient reaction time to effect disinfection of these organisms by ozone generated by UV radiation. The fact that the odor of ozone was present above the spa water indicates that contacting also was inefficient.
Fernández-Luna, Álvaro, Leonor Gallardo, María Plaza-Carmona, Jorge García-Unanue, Javier Sánchez-Sánchez, José Luis Felipe, Pablo Burillo, and Ignacio Ara. "Respiratory function and changes in lung epithelium biomarkers after a short-training intervention in chlorinated vs. ozone indoor pools." PloS one 8, no. 7 (2013): e68447.
Abstract excerpts:
Swimming in indoor pools treated with combined chemical treatments (e.g. ozone) may reduce direct exposure to disinfection byproducts and thus have less negative effects on respiratory function compared to chlorinated pools.
The aim of this study is to analyze the effects of a short-term training intervention on respiratory function and lung epithelial damage in adults exercising in indoor swimming pool waters treated with different disinfection methods (chlorine vs. ozone with bromine).
... Despite lung function being similar in both groups, a higher lung permeability in CP compared to OP swimmers was found after a short-term swimming program. Combined chemical treatments for swimming pools such as ozone seem to have less impact on lung epithelial of swimmers compared to chlorinated treated pools.
Freije, Matthew R. "Spas, Hot Tubs, and Whirlpool Bathtubs: A Guide for Disease Prevention." [PDF] USA: HC Information Resources Inc (2000): HC Information Resources Inc. PO Box 2109 Fallbrook CA 92088-2109, USA Tel: 1-800-801-8050 (USA and Canada) or +1-760-451-1020 Fax: 1-800-290-1967 (USA and Canada) or +1-619-839-3166 hcinfo@hcinfo.com http://hcinfo.com, retrieved 2016/03/22, original source: http://www.whtlimited.com/doc/lib/102/spa-whirlpools-guidance.pdf
Abstract - Excerpts:
Spas and hot tubs are not the same as whirlpool baths. Spas and hot tubs are used for recreation rather than for bathing. Many private spas are located outdoors. They are not drained after each use. Most have heaters. The water is treated and filtered.
Spas, hot tubs, and whirlpool bathtubs can provide a fertile breeding ground for many microbes, including organisms that cause disease.
At greatest risk of illness and death are pregnant women, those with weakened immune systems, small children, the elderly, and smokers, which, combined, make up 25% of the US population.6 Individuals in generally good health can also become infected, particularly if the microbial level is high.
Each person releases organic matter while using a spa or whirlpool bath, including dead skin cells, perspiration, a small amount of urine, oils, and cosmetics. Organic matter builds up much faster in spas than in swimming pools because the volume of water per bather is much lower and the water is usually warmer. If it is not removed, organic matter will become a haven and food source for microbes.
The build-up of contaminants can be reduced by restricting the number of bathers according to the size of the spa and by requiring users to shower before entering, using soap to remove body oils.
Bubbles produced by air jets are an efficient means of transmitting microbes from the water to the bather. The bubbles burst at the water's surface, lofting fine droplets into the breathing zone of the users. People outside a spa can also be affected if the spray is carried by air currents or a ventilation system.
The illness most frequently associated with spas and whirlpool baths is dermatitis, a skin infection caused by Pseudomonas aeruginosa bacteria (Pseudomonas bacteria can also cause other illness).
Outbreaks of skin disease caused by Pseudomonas aeruginosa in 951 individuals were reported to the Centers for Disease Control and Prevention (CDC), Atlanta, USA, from 1985 to 1994.
During the same period, five outbreaks of Pontiac fever were reported, affecting a total of 63 people. Pontiac fever is a flu-like illness that is caused by Legionella bacteria. Experts estimate that a very low percentage of spa-related illness is reported to health authorities, so the actual number of cases that occurred from 1985 to 1994 is probably much higher than the reported numbers. In addition, only outbreaks associated with public spas are reported.
The incidence of disease associated with residential spas is likely much higher.
Glazer, Craig S., John W. Martyny, Ben Lee, Tracy L. Sanchez, Tricia M. Sells, Lee S. Newman, James Murphy, Leonid Heifets, and Cecile S. Rose. "Nontuberculous mycobacteria in aerosol droplets and bulk water samples from therapy pools and hot tubs." Journal of occupational and environmental hygiene 4, no. 11 (2007): 831-840.
Abstract:
Hot tub exposure has been causally associated with a steroid-responsive, granulomatous lung disease featuring nontuberculous mycobacterial (NTM) growth in both clinical and environmental samples. Little is known regarding prevalence of and risk factors for NTM-contamination and associated illness in these settings.
In this study, the frequency of NTM growth and aerosolization in 18 public hot tubs and warm water therapy pools and the factors associated with mycobacterial growth were analyzed.
Each site was characterized by water chemistry analysis; a questionnaire on maintenance, disinfection, and water quality; and air and water sampling for quantitative NTM culture. NTM were detected in air or water from 13/18 (72%) sites; a strong correlation was found between the maximum air and water NTM concentrations (rho 0.49, p = 0.04).
Use of halogen (chlorine or bromine) disinfection was associated with significantly lower air and water concentrations of NTM compared with disinfection using ultraviolet light and hydrogen peroxide (p = 0.01–0.04). Higher water turnover rates were also associated with lower air and water NTM concentrations (p = 0.02–0.03).
These findings suggest that NTM are frequently detectable in the air and water of spas and therapy pools and that particular maintenance and disinfection approaches affect NTM bioaerosol concentrations in these settings.
Highsmith, Anita K., and Ann Marie McNamara. "Microbiology of recreational and therapeutic whirlpools." Toxicity Assessment 3, no. 5 (1988): 599-611.
Abstract:
Over half of the reported outbreaks of whirlpool-associated dermatitis and folliculitis have been caused by Pseudomonas aeruginosa, serotype 011. Illness caused by Staphylococcus aureus, Legionella pneumophila, Mycobacterium, Streptococci, and Acanthamoeba have been infrequently reported. The presence of microorganisms in water is not the only factor involved in infection transmission. Other factors in disease may be individual host susceptibility, immersion time, bather load, gender, and use of clothing.
A bather's risk for P. aeruginosa dermatitis or folliculitis appears to depend on immersion in water colonized by P. aeruginosa, skin hydration with altered skin flora, and toxic reactions to extracellular enzymes or exotoxins produced by P. aeruginosa. Outbreaks of illness appear to be directly related to inadequate operational and maintenance procedures. Chemical and physical parameters should be routinely monitored. Microbiologic sampling of whirlpool water is not advised except in outbreak investigations.
Hoff, J. C., “Inactivation of Microbial Agents by Chemical Disinfectants”, U.S. Environmental Protection Agency, Report no. EPA/600/2-86/ 067, 1986.
Hoigne, J. and H. Bader, “Rate Constants for Reaction of Ozone with Organic and Inorganic Compounds - I: Non-dissociating Organic Compounds”, Water Research, 17(1983a):173- 183.
Hoigne, J. and H. Bader, “Rate Constants for Reaction of Ozone with Organic and Inorganic Compounds – II: Dissociating Organic Compounds”, Water Research, 17(1983b):184- 185.
Hoigne, J., H. Bader, and W. R. Haag, “Rate Constants for Reaction of Ozone with Organic and Inorganic Compounds - III: Inorganic Compounds and Radicals”, Water Research, 19(1985):993-1004.
Kon, Deborah, "Ozone in Your Pool and Spa", [Web article] Ultra Pure, 1175 Appleby Line Burlington ON L7L 5H9 Tel:: 877 281-7603 Website: www.waterquality.net
Deborah Kon is the laboratory manager at UltraPure Water Quality Inc, a manufacturer of Ozone generators for residential pools and spas.
retrived 20167/03/22, original source: http://www.waterquality.net/upload/fmarticleso/Ozone\_In\_Your\_Pool\_Spa\_13.pdf
Kinman, R.N., Water and Wastewater Disinfection with Ozone”, Critical Reviews of Environmental Control, 5(1975):141-152
Kurzman, G. E., “Ozone-Granular Activated carbon Removal of Ammonia and Urea from Simulated Spa Water.” NSPI Symposium Series Volume IV, 1999, pp. 44–52.
Kurzman, G. E., “Ozone-Granular Activated carbon for Disinfection and Purification of Swimming Pool Water”, in Ozone Treatment of Waters for Swimming Pools, R. Rice, Ed., International Ozone Association, Norwalk, CT, 1982, p. 106
Lumb, Richard, Richard Stapledon, Andrew Scroop, Peter Bond, David Cunliffe, Allan Goodwin, Robyn Doyle, and Ivan Bastian. "Investigation of spa pools associated with lung disorders caused by Mycobacterium avium complex in immunocompetent adults." Applied and environmental microbiology 70, no. 8 (2004): 4906-4910.
Abstract:
Three cases of Mycobacterium avium complex-related lung disorders were associated with two poorly maintained spa pools by genotypic investigations. Inadequate disinfection of the two spas had reduced the load of environmental bacteria to less than 1 CFU/ml but allowed levels of M. avium complex of 4.3 × 104 and 4.5 × 103 CFU/ml. Persistence of the disease-associated genotype was demonstrated in one spa pool for over 5 months until repeated treatments with greater than 10 mg of chlorine per liter for 1-h intervals eliminated M. avium complex from the spa pool.
A fourth case of Mycobacterium avium complex-related lung disease was associated epidemiologically but not genotypically with another spa pool that had had no maintenance undertaken.
This spa pool contained low numbers of mycobacteria by smear and was culture positive for M. avium complex, and the nonmycobacterial organism count was 5.2 × 106 CFU/ml. Public awareness about the proper maintenance of private (residential) spa pools must be promoted by health departments in partnership with spa pool retailers.
Matsumoto, Nobuo, and Kenzo Watanabe. "Foot prints and future steps of ozone applications in Japan." (1999): 127-138.
Abstract:
Although the first trials with ozone in Japan were made in the early 1930s, significant growth did not occur until 1960-1980. Ozone has been applied for drinking water, wastewater, odor control, swimming pools, laundries and semiconductor manufacture. Recently, the Japan Ozone Association has formed a task force to address the Cryprosporidium issue.
Moraga-McHaley, Stephanie Ann, Michael Landen, Heidi Krapfl, and C. Mack Sewell. "Hypersensitivity pneumonitis with Mycobacterium avium complex among spa workers." International journal of occupational and environmental health 19, no. 1 (2013): 55-61.
Papadopoulou, Chrissanthy, Vangelis Economou, Hercules Sakkas, Panagiota Gousia, X. Giannakopoulos, Catherine Dontorou, George Filioussis, Helen Gessouli, Panagiotis Karanis, and Stamatina Leveidiotou. "Microbiological quality of indoor and outdoor swimming pools in Greece: investigation of the antibiotic resistance of the bacterial isolates." International journal of hygiene and environmental health 211, no. 3 (2008): 385-397.
Abstract:
During 1997–2005, the microbiological quality and susceptibility of bacterial isolates of swimming pool waters were investigated. A total of 462 water samples were collected from three indoor swimming pools (a teaching pool, a competition public pool, a hydrotherapy pool) and two outdoor swimming pools (a hotel semi-public and a residential private pool) in Northwestern Greece. All water samples were analyzed for the presence of bacteria, protozoa and fungi and susceptibility tests were performed for the bacterial isolates. Sixty-seven percent of the examined water samples conformed to the microbiological standards and 32.9% exceeded at least one of the indicated limits.
Out of 107 bacterial isolates, 38 (35.5%) resistant strains were detected. Multi-resistant Pseudomonas alcaligenes, Leuconostoc, and Staphylococcus aureus (isolated from the teaching pool), Staphylococcus wernerii, Chryseobacterium indologenes and Ochrobactrum anthropi (isolated from the competition pool), Pseudomonas aeruginosa, P. fluorescens, Aeromonas hydrophila, Enterobacter cloacae, Klebsiella pneumoniae and S. aureus (isolated from the hydrotherapy pool) and A. hydrophila (isolated from the hotel pool) were detected.
The swimming pool with the poorest microbiological quality (THC 500 cfu/ml in 12.1% of the samples, P. aeruginosa counts 1500 cfu/100 ml in 6% of the samples) and the highest prevalence of multi-resistant isolates (73.6%) was the hydrotherapy pool.
No Cryptosporidium or Giardia cysts and no Legionella, Mycobacteria and Salmonella were detected, but there were isolations of Candida albicans, Aspergillus spp., Mucor spp., Alternaria spp., Rhizopus spp., Trichophyton spp., and Penicillium spp.
Powick, D. E. J. "Swimming pools–brief outline of water treatment and management." Water Science and Technology 21, no. 2 (1989): 151-160.
Abstract:
A brief history of the development of swimming pool water treatment and management has been discussed, applicable to both large and small pools. An outline of typical bathing loads and current methods of water treatment has been presented with particular emphasis being given to disinfection.
Chlorine has been the traditional sole disinfectant used since the 1920's but alternatives are continually being sought. Chief amongst the alternatives to date has been ozone, used in conjunction with chlorine. Ozone acts as a powerful oxidiser and disinfectant but has little residual effect. Chlorine is therefore used to provide a residual in the pool. Current British trends in pool design and treatment have been noted.
Rice, Rip G. "Ozone in the United States of America--state-of-the-art." (1999): 99-118.
Rigas, Fotis, Athina Mavridou, and Athanassios Zacharopoulos. "Water quality of swimming pools in Athens area." International Journal of Environmental Health Research 8, no. 3 (1998): 253-260.
Abstract:
In this work a representative sample of 11 indoor and outdoor swimming pools were investigated with respect to critical physicochemical, health-related, microbiological and technical parameters. These pools were used either as competition (athletic) or as recreation pools. Useful correlations of the above parameters were deduced and properly attributed. Results were checked against well-established standards, such as DIN 19643, showing poor compliance with them in all parameters investigated.
Thus, compliance for health-related parameters varied from 0 to 100%, for physical and chemical parameters from 20 to 100%, for microbiological parameters from 45 to 91% and for technical parameters from 27 to 36%.
The most critical parameters implicated for poor water quality were Redox potential, turbidity and the appearance of certain opportunistic pathogens ( Staphylococcus aureus and Pseudomonas aeruginosa ). These were attributed to poor process design of pools and lack of sufficient vocational training of the technical personnel operating the water treatment installations.
Saha, Ratul, Richard Martin, and Robert Donofrio. "Efficacy of Ozone Treatment Systems Against Microorganisms: Current Methodology and Future Approaches for Evaluating Novel Disinfection Technologies."
Steinbruchel, A., R. G. Rice, and R. Spangenberg. "First year operation report of the corona discharge ozone swimming pool water treatment systems at the peck aquatic facility, Milwaukee, Wisconsin." Ozone: science & engineering 13, no. 4 (1991): 463-478.
Stewart, Mic H. "Spa and Hot Tub Microbiology." Encyclopedia of Environmental Microbiology.
Tiefenbrunner, F., “Problems with the Direct Ozonation of Swimming Pool Water”, in Ozone Treatment of Waters for Swimming Pools, R. G. Rice, Ed., International Ozone Association, Norwalk, CT, 1982, p. 152.
Wojtowicz, John A. "Use of ozone in the treatment of swimming pools and spas." [PDF] Journal of the swimming pool and spa industry 4, no. 1 (2001): 41-53. Retrieved 2016/03/22, original source: http://jspsi.poolhelp.com/articles/jspsi\_v4n1\_pp41-53.pdf
Abstract:
Although ozone is an effective disinfectant, it cannot be used as a primary sanitizer because of its volatility, toxicity, and short lifetime. Since ozone is unstable and hazardous, it has to be produced on– site from air by ozone generators (ozonators). Commercial units employ ultraviolet light (UV lamps) or electrical discharge (i.e., corona discharge or CD). UV ozonators produce very low concentrations of ozone compared to CD ozonators, i.e., < 0.1 vs. ~1.5 wt. %.
Despite its high oxidation potential, ozone reacts very slowly with bather contaminants such as ammonia, monochloramine, urea (the main contaminant), and creatinine, even at high ozone and contaminant concentrations. Both chlorine and bromine are more effective than ozone in oxidation of these contaminants. The very low ozone concentrations produced by UV ozonators makes them even less effective than CD ozonators in oxidation of bather contaminants.
A number of UV ozonators have been evaluated and found to be unsuitable for pool or spa use. Although UV ozonator manufacturers typically claim lower chlorine consumption (typically 60 to 90%) and the ability to operate pools and spas at lower chlorine concentrations, no independent data are provided to support these claims.
In Europe, CD ozone is used in an integrated system such as the German–designed ozone–granular activated carbon (GAC) process that employs flocculation, sand filtration, ozonation, GAC filtration, and chlorination and also includes a water purge. In DIN (German Industry Standard) based installations, the reduction in chemical oxygen demand (COD) of the water (other than ammonia and urea) is improved by 20% over the same process without ozone/GAC, and also reduces operating costs by 20%; however this system is cost effective only for large heavily used pools.
In North America, variations of the ozone–GAC process are employed that treat only a portion of the water resulting in lower COD reductions than obtained using DIN–based systems.
Wojtowicz, J. A. “Fate of Nitrogen Compounds in Swimming Pool Water”, Symposium Series Vol. III, pp 40-44, 1998, NSPI National Meeting, New Orleans, LA.
Wojtowicz, J. A., “Chemistry of Nitrogen Compounds in Swimming Pool Water”, Journal of the Swimming Pool and Spa Industry, 4(1)(2001):30- 53.
Zwiener, Christian, Susan D. Richardson, David M. De Marini, Tamara Grummt, Thomas Glauner, and Fritz H. Frimmel. "Drowning in disinfection byproducts? Assessing swimming pool water." Environmental Science & Technology 41, no. 2 (2007): 363-372.
Abstract:
Disinfection is mandatory for swimming pools: public pools are usually disinfected by gaseous chlorine or sodium hypochlorite and cartridge filters; home pools typically use stabilized chlorine. These methods produce a variety of disinfection byproducts (DBPs), such as trihalomethanes (THMs), which are regulated carcinogenic DBPs in drinking water that have been detected in the blood and breath of swimmers and of nonswimmers at indoor pools. Also produced are halogenated acetic acids (HAAs) and haloketones, which irritate the eyes, skin, and mucous membranes; trichloramine, which is linked with swimming-pool-associated asthma; and halogenated derivatives of UV sun screens, some of which show endocrine effects.
Precursors of DBPs include human body substances, chemicals used in cosmetics and sun screens, and natural organic matter. Analytical research has focused also on the identification of an additional portion of unknown DBPs using gas chromatography (GC)/mass spectrometry (MS) and liquid chromatography (LC)/MS/MS with derivatization.
Children swimmers have an increased risk of developing asthma and infections of the respiratory tract and ear. A 1.6−2.0-fold increased risk for bladder cancer has been associated with swimming or showering/bathing with chlorinated water. Bladder cancer risk from THM exposure (all routes combined) was greatest among those with the GSTT1-1 gene.
This suggests a mechanism involving distribution of THMs to the bladder by dermal/inhalation exposure and activation there by GSTT1-1 to mutagens. DBPs may be reduced by engineering and behavioral means, such as applying new oxidation and filtration methods, reducing bromide and iodide in the source water, increasing air circulation in indoor pools, and assuring the cleanliness of swimmers. The positive health effects gained by swimming can be increased by reducing the potential adverse health risks.

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Anon: a typical ozone generator for a private whirlpool bath or spa generates 300 mg/hour of ozone gas.

How much ozone is OK? Subjectively, up to the point of smelling ozone; if you smell ozone then the ozone level is too high and may be unsafe. All of the ozone generator providers can be expected to include a warning in their instructions that breathing ozone gas is harmful.

Watch out: You want to follow the instructions for your specific ozone sanitizer for your spa - by brand and model.

An EXAMPLE Spa ozone sanitizer instructions can be read in the CMP manual I'll cite below. However you'll see that other than installing the equipment properly, the company's manual does not give a quantitative measurement of the "right" ozone level for your spa. I suspect this is in part because of the difficulty of defining a precise and accurate measurement procedure that can handle all of the enormously variable installation situations.

CMP DEL OZONE 25/50/100 INSTALLATION INSTRUCTIONS & PRODUCT MANUAL [PDF] CMP, LLC 36 HERRING ROAD, NEWNAN, GA 30265 USA Tel: 800.733.9060 ret. 2019/08/10 original source: https://www.c-m-p.com/wp-content/uploads/2018/05/DEL-Ozone-25\_50\_100-Manual-1.pdf Web: https://www.c-m-p.com

what is the ideal levels of ozone in spa water
Thanks
dave
dave98412@btinternet.con

Thanks for an important question on how ozone can be used in spas or whirlpool baths or hot tubs, and its limitations, and safety.

A spa can generate and use ozone safely while the spa is in use PROVIDED it is working properly and is designed to keep the ozone where it belongs - in the plumbing system, not on the spa occupants.

I'd agree that ozone exposure can be a health concern; ozone is a powerful oxidant that can at high concentrations damage the lungs.

A broad "rule of thumb" is that if you smell ozone the level is high enough that you ought to avoid it; if not, probably not;

In general an ozone generator on a spa is used to reduce the amount of disinfectant needed (it cannot eliminate the need for disinfectant); but ozone should not be entering the space occupied by the spa users.

For example here is an excerpt from experts:

A properly designed ozone or UV system will reduce the amount of chlorine or bromine required.3,5 Ozone is especially effective as a supplement because it destroys matter that "uses up" the chemicals.

Ozone is effective only if the system is sized and designed properly.
The ozone generator must make enough ozone. Also, ozone systems must treat the spa water in an isolated contact chamber

rather than injecting ozone into the spa itself. -

FREIJE, Matthew R. Spas, Hot Tubs, and Whirlpool Bathtubs: A Guide for Disease Prevention. USA: HC Information Resources Inc, 2000, p. 1-3. http://www.whtlimited.com/doc/lib/102/spa-whirlpools-guidance.pdf

Also:

The half–life of ozone in tap water at 20°C is less than 30 minutes. In addition to this thermal decomposition, aqueous ozone is also decomposed by sunlight. Because ozone is a gas, it tends to escape from aqueous solution. This tendency and the fact that ozone is toxic (the maximum allowable concentration in air is only 0.1 ppm for an 8–hour exposure), is the reason that ozone cannot be used as a primary sanitizer. - FREIJE, Matthew R. Spas, Hot Tubs, and Whirlpool Bathtubs: A Guide for Disease Prevention. USA: HC Information Resources Inc, 2000, p. 1-3.
http://www.whtlimited.com/doc/lib/102/spa-whirlpools-guidance.pdf

Should the spa controller allow ozone generation while persons use the spa ? For example, in a two pump spa system, the ozone generator is ON when the Pump 1 low speed is in operation. When Pump 1 is switched to FULL SPEED, the ozone generator is OFF

. However, when the Pump 1 is in low speed and the Pump 2 is ON, the ozone generator continues to be ON. Spa users would be exposed to ozone generated and circulated by Pump 1 low speed operation. Is this a health concern ?

...

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