By Cameron Tapp

There is a vibrant recreational water market in need of the services of the skilled water treatment professional. Opportunities include installation and service of municipal,  commercial and residential pools and spas and a host of specialty waterscapes and features from backyard fountains and waterfalls up to theme park-size features complete with water slides, fountains and flumes. This is a significant market: for pools and spas alone, initial and aftermarket sales are estimated to be about $20.8 billion (US).1
Ozone is well positioned to be the sanitation system of choice in the health and environmentally conscious market today, for a number of good reasons:

  • Ozone is by far the strongest oxidizer commercially available.
  • Ozone is generated as needed on site (no storage space is needed as for other sanitizers).
  • Ozone is the only disinfectant that is also a flocculant that cleanses water of organic and inorganic impurities.
  • Ozone is the most practical method for control of Cryptosporidium and Giardia cysts

The advantages of pre-oxidation
Ozone provides pre-oxidation in public pools and spas that use chlorine in addition to ozone for sanitation. By pre-oxidizing the water prior to chemical introduction, combined chlorine (spent chlorine that forms harmful chloramines and THMs in pool water) is kept at a minimum. This is because ozone disposes of the contaminants that create the primary demand for chlorine in terms of oxidation, dramatically reducing combined chlorine that can be formed—in many cases eliminating it altogether. Chloramine formation (and the resulting THMs) is the number one problem in chlorinated pool sanitation—and it can consistently be remedied only by ozone. In fact, ozone oxidizes chloramines that have already formed (however slowly).

Additional advantages
Ozone reduces the amount of chemical(s) required for residual sanitizer and pH adjustment. The elimination of chloramines provides the additional advantages of improved bather comfort, elimination of pool odor (in natatoriums) and improved disinfection and water clarity.

Different applications, different combinations
In commercial applications, ozone/bromine and ozone/chlorine are the most common partners. In residential applications, ozone can even stand alone with trace amounts of algaecide.

Ozone and bromine are chemically synergistic. With minimal amounts of ozone, pool water acts as a bromine regeneration system; the bromine provides residual sanitation and algae control while ozone does the heavy lifting for disinfection. The basic operating principle of this combination is what makes it so effective: is has the ability to constantly regenerate hypobromous acid from the bromide ions present in the pool water.
                                           Br – + O3+ H2O = HOBr + OH- + O2
There are pros and cons to this combination:


  • Excellent synergy
  • Little pH adjustment required
  • Easy to handle
  • Fast microbe kill: 30 to 120 seconds in small contact vessel (CT) or no CT at all
  • Good algae control
  • Minimal odor


  • Bromine cannot be stabilized
  • Cost
  • Cloudy water/swimmer’s itch
  • Low ORP levels

With these factors in mind, the best applications for ozone/bromine fall into four groups: those with light-to-medium bather loads; in pools and spas with good filtration (minimum six-hour turnover rate); where handling and storing chemicals is an issue and in applications where minimal room is available for contact vessel(s).

This combination’s basic advantage depends on ozone pre-oxidation to reduce contaminant ‘load’ on chlorine to eliminate chloramine formation, whereby chlorine is required to act only as a residual sanitizer. It is important to note that unlike the synergy shown with the bromide ion, ozone has no such synergy with the chloride ion. Ozone will oxidize free available chlorine at a very slow rate; the slowness of the reaction is due to the complexity of the chlorine molecule and the primary demand from other contaminants in the water reacting with ozone first (more quickly). The pros and cons of using ozone with chlorine are:


  • Strong oxidation
  • Stable chemistry
  • Less expensive


  • Zero synergy
  • Requires pH control
  • Chlorine is more difficult to handle

The best applications for this combination are pools with high bather loads or other extreme environmental conditions and pools with less proficient filtration. Ideally a pool should be operated with 0.2-0.5 ppm ozone (700-800 mV ORP); an alternative level of 0.5-1.0 ppm (700-800 mV ORP) can also be used.

Additional suggestions

  • Use a flocculation program with all high-rate sand filters, especially in bromine pools.
  • Use a flocculant, particularly with sand filtration.
  • Shock all pools on a regular basis.
  • Drain at least 50 percent of a bromine pool annually.
  • Maintain lowest possible residual sanitizer level (0.2-1.0 ppm) @ 750-800 mV ORP on chlorine pools.
  • Maintain pH range of 7.2-7.4 for chlorine pools, 7.4-7.8 for bromine pools.

Mass transfer

  • Efficient ozone dissolution in water
  • Pressure, concentration and temperature
  • Air to water volume ratio
  • Ozone concentration
  • Bubble size

Profit potentials
Water industry trade shows indicate strong growth in the pool and spa sector. The International Pool & Spa Expo was up 28 percent in 2005 as compared with the previous year; the AQUA Show had an increase in buyers of 16 percent last year, while the N.E. NSPI show was the largest in 23 years. The strength of the market encourages new products, while overall the sales in this category reflect the larger, growing quality-of-life market. Water quality products hold cross-market potential.

Other applications abound
From the large scale (water parks) to the small (residential koi ponds) there are applications of every imagineable size and scope both across the US and globally.


  1. According to the Association of Pool and Spa Professionals, 2005, as reported in the Instant Background Report for Swimming.

About the company    
Cameron Tapp is a principal of ClearWater Tech, LLC, a leading designer, manufacturer and marketer of ozone generation equipment and related components serving a wide range of air and water purification applications and markets. ClearWater Tech is a technical leader in the field, with patents pending on multiple ozone-related products and processes. The company offers a complete range of products for commercial and residential pools and holds dominant positions in two newly expanding markets for ozone equipment: commercial laundries and whole-house residential air treatment. The firm was founded in 1986 and was acquired by AWTP and Waud Capital in 2005. To date, ClearWater Tech has over 20,000 installations on six continents. Clear Water Tech, 850-E Capitolio Way, San Luis Obispo, CA 93401. Toll free: (800) 262-0203; [email protected];



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