Ozone - the Silent Server of the Ozone Industry

Trends in the use of Ozonators In Spas

Ozone’s power to destroy bacteria, pathogens and harmful chemicals was not well known within the industry when ozonator were first introduced for spas in 1977. It had been known for years that ozone, a form of oxygen, had the highest available oxidation potential and was a powerful sanitizer, however, system complexity and reliability had limited its usefulness. Early attempts to use ozonators were made by inserting ozone into the air jets in the spa. Although this method was effective, ozone was utilized inefficiently and produced potentially irritating levels of ozone off-gas (greater than .1 ppm) to the spa occupants. (Ref 1)

Testing and experience demonstrated that not only was ozone a powerful sanitizer and effective oxidizer in the spa, but that it was extraordinarily synergistic with bromine and chlorine. Ozone also acted as a natural flocculent which dramatically cleaned water (Ref 2). Major gains were achieved in VUV ozonator output, reliability, cost effectiveness, ruggedness, and manufacturing efficiency. Corona discharge were not used because of they provided inconsistent outputs, sporadic off-gassing in excess of .1 ppm, and poor reliability .

In 1984, Prozone introduced and patented the concept of contacting ozone with an independent bypass system (Ref 4). The bypass method provided very high ozone absorption, created very little off-gas and allowed an increase in the amount of ozone that could be used in a spa. The additional ozone was required to oxidize contaminants out of the water, but more importantly, it effectively destroyed pseudomonas (spa rash), which had become a hazard in poorly maintained spas. Ultra violet ozone systems thus became a standard application on portable spas. A total dose rate of 4 grams per day was determined to satisfy the oxidation requirements of a typical 500 gallon spa.

Although ozone is an effective sanitizer, oxidizer; operates without maintenance, its transient nature, difficulty to measure and invisibility require that its effectiveness be demonstrated through the water quality it produces and biological testing. The use of a low level residual halogen (.5 ppm) with ozone is still desirable for high bather loads and can be easily measured. Ozone will reduce the total amount of halogen require to maintain a residual.

Many spa operators and manufacturers over the years have questioned the need for higher levels of ozone. In the early 1990's, in order to reduce costs and still maintain the low off-gassing limit of .1 PPM of ozone in air, ( established by the EPA and required by UL and NSF), many ozone manufactures reduced the output of their ozonators to less than 3 grams per day to simplify their contact systems. These systems, although biologically effective had marginal capability to oxidize contaminants.

As the industry has matured and become more knowledgeable, the need for increased performance of ozonator systems has become readily apparent. The potential existence of lethal organisms such as Legionnaire’s Disease and E. coli in spas, the use of bromine compounds (which increase ozone requirements), emphasis on health, and the toxic effect of chemical byproducts have made spa manufacturers increase dose rates to greater than 8 grams per day by using higher output ozone generators which run for longer periods of time and effective, free standing bypass contactors systems. These systems may include dynamic injectors, extended bypass tubing, static mixers, diffusers, off-gas separators, 24 hour per day ozonators, and compressor driven ozonators. Many variation of the components are now being integrated into the plumbing of the spa or introduced as a stand alone packaged systems. (Ref. 5). With NSF and UL listed equipment, they can be tested and classified as "Sanitation Systems". (Ref.3)

In summary, ozone continues to be the silent server of the spa industry adding performance, safety, and water quality for the spa user.

Ref. 1 "Spas have unique needs"., Pool and Spa News. 1984

Ref. 2 "Testing of Ozonators for use in Spas." Miracopa County Health Dept. 1984

Ref. 3 NSF Standard 50

Ref. 4 Prozone Patent #5,075,016

Ref. 5 Web "prozoneint.com"

Author Biography

Ronald Barnes, BS Physics, MS EE, Founder and CEO of Prozone International, Visionic, Inc, and Vistek which are manufacturers of ozone and electro-optical equipment. Mr. Barnes has 40 years of product development experience in aerospace, optics, and ozone technology. He has been an advisor to many committees and holds several patents.