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Ron George of ETS (Engineered Treatment Systems) is “Questioned” by a Recognized UV Authority

Posted: August 20th 2010
Updated: September 29th 2010

FOR THE FIRST TIME a respected authority in Ultraviolet Disinfection has questioned a UV Manufacturer’s irresponsible actions of misrepresenting scientific fact (UV Lamp technology). The “Tech Talk” Article written by Ron George of ETS (Engineered Treatment Systems, LLC in Beaver Dam, WI.), In the May 2010 issue of Aquatics International, alludes that Medium-Pressure is a more effective UV Technology than Low-Pressure when applied as germicidal disinfection. Thankfully, Dr. James R. Bolton (President of Bolton Photosciences, Inc.) had the courage to respond publicly to this article.

Please be aware that Dr. Bolton is not advocating one system over the other; he strives for accurate information on all UV technologies.

Please read Read Dr. Bolton’s rebuttal, as it appeared in the September 2010 issue, to Ron George’s (ETS) Aquatics International “Pressure Situation” Article and Ron George’s misleading Medium-Pressure Lamps vs. Low-Pressure Lamps article below. Then you can see other responses, including our own, just below that.

          Have UV Lamp questions? Contact us at info@emperoraquatics.com.

"Pressure Situation"
by Ron George - printed in Aquatics International May 2010 Issue


James R. Bolton, Ph.D.
President of Bolton Photosciences Inc.
Edmonton, Alberta, Canada

Sent to Aquatics International as shown here.


Unfortunately, several statements in that article are, in my opinion, either incorrect or highly misleading. I have structured my response by quoting Ron George’s paragraphs and then followed by my specific responses.

“They discovered low-pressure technology that was successful for drinking water did not work as effectively in pools. That led UV-lamp manufacturers to develop medium-pressure lamp (MP) technology. The recreational pool market for UV systems then quickly became successful.”

“Several significant factors in pool applications make LP lamp technology unsuitable for disinfection and the destruction of chloramines. They are as follows:

The wavelength emitted by LP lamps is narrow — 254 nm. This radiation is capable of destroying monochloramine, which would be effective if the water were being treated in its entirety in one single pass.”

“That is not the case. Therefore, trichloramine and dichloramine, which are far less healthy, are produced from the monochloramine still in the untreated water. Once the tri and di appear, LP cannot effectively destroy them because di and tri compounds absorb UV light at 297nm and 345nm, according to research from Purdue University.”

The statements in the above three paragraphs are either not true or highly misleading. In fact, according to the paper by Li and Blatchley (Ling, J; Blatchley III, E R, “UV photodegradation of inorganic chloramines”, Envir. Sci. Technol. 2009, 43(1), 60–65.), monochloramine and trichloramine have almost the same molar absorption coefficient (388 and 367 M–1 cm–1, respectively) at 254 nm. Only dichloramine has a lower value (142 M–1 cm–1). But the rate of degradation is proportional to the product of the fraction of UV light absorbed (related to the molar absorption coefficient and the concentration) and the quantum yield. The quantum yields for the photodegradation of mono- di- and trichloramine are 0.62, 1.80 and 1.85, respectively. Thus dichloramine will degrade at about the same rate as monochloramine and trichloramine will degrade about three times faster than monochloramine at 254 nm.

“The temperature of pool water is normally around 80 to 85 degrees; spas are in the 95 to 104 degree range. Low-pressure lamps have a relatively low surface temperature; therefore, the influence of water temperature is significant. The optimal water temperature for LP lamps is 68 degrees Fahrenheit (20 degrees Celsius). At temperatures above that, the UV output drops off significantly.”

This is not true — the optimal surface temperature for a low pressure UV lamp is 40 °C. Low pressure high output lamps operate at a surface temperature of about 100 °C.

“Medium-pressure lamps operate at a much higher temperature and can operate effectively in a much greater temperature range with no effect on the UV output, according to Dr. James Bolton of Bolton Photosciences Inc. in Edmonton Canada.”

This statement is true; however, medium pressure UV lamps have about half the germicidal efficiency as that of low pressure and low pressure high output lamps.

“Low-pressure lamps are vulnerable to photorepair when an organism is exposed to sunlight for a short period of time, approximately 30 to 180 minutes.”

“What does this mean? In swimming pools, the water passes through the UV chamber after filtration and returns to the pool during the turnover cycle. At this time, the DNA that was broken down by LP lamps can repair itself. We are, in effect, showing that we are “destroying” the parasite when it passes through the UV chamber; it is, however, reappearing in the pool water only to be reactivated again. This is a cycle that repeats itself.”

“However, studies have shown medium-pressure lamps break down the DNA and do not allow photorepair, according to a study published in the journal Applied and Environmental Microbiology by researchers J.L. Zimmer and R.M. Slawson.”

The evidence for the statements in the above three paragraphs is not clear in the literature. For example, Guo et al. (Guo, M; Hu, H; Bolton, J R; Gamal El-Din, M, “Comparison of low- and medium pressure ultraviolet lamps: Photoreactivation of Eschericia coli and total coliforms in secondary effluents of municipal wastewater treatment plants”, Water Res. 2009, 43, 815–812.) found no difference in photoreactivation between low- and medium pressure UV lamps for the same germicidal UV dose.

“Medium-pressure lamps break down organics, assisting in water clarity. Low-pressure lamps will not, according the U.S. Environmental Protection Agency.”

This statement is highly misleading. What matters in photolysis reactions is the product of the fraction of UV light absorbed (related to the molar absorption coefficient and the concentration) at a given wavelength and the quantum yield at that wavelength. So a comparison between a low pressure and a medium pressure UV source requires extensive calculations. The answer may be one way or the other depending on the photolysis system.

“Low-pressure systems use multiple lamps to achieve enough intensity to treat the water. This creates several issues. Typically, several lamps are monitored by a single sensor to be able to verify the proper dose and intensity is being applied. One can only be sure that the flow nearest the closest lamp is effectively being disinfected. Second, if one of several lamps has failed, do you replace them all? How do you monitor the lamp hours? Do you number each one and keep a record of each?”

In drinking water UV reactors with multiple UV lamps, the system is ‘validated’ by biodosimetry. There is a requirement for periodic monitoring of the system to make sure that the quartz sleeves are not fouled. Also UV lamps must be replaced after a certain lifetime. Very large municipal UV drinking water systems have been installed (over 100 MGD) and there have been few if any problems in their operation.

“Multiple lamps with LP technology mean more maintenance issues. Most LP manufacturers do not provide automatic wiper systems to keep the quartz clean; they are simply not practical with multi-lamp LP systems. This then requires manual cleaning, which is very time-consuming. Again, when one or more lamps fail, do you replace them all?”

This is simply not true. There are hundreds or even thousands of UV systems in operation today that have multiple low pressure or low pressure high output lamps and do have effective automatic cleaning systems. Many have been in operation for years with very few, if any, problems.

“Research is an important tool in developing new products and testing existing products to meet the requirements of our industry. But it is important to review the results objectively rather than use those parts of the study to advance one’s interests.”

“For example, several manufacturers have cited a recent study on the “Impact of Chlorine and Monochloramine on Ultraviolet Light Disinfection,” from Duke University/University of North Carolina. They extract data from this study, trying to claim that LP technology is more effective than MP technology.”

“The problem with the extrapolation is that they fail to cite the conclusion arrived at or the conditions under which the study was conducted. The study involves dosing from 300 mJ/cm2 to 1500 mJ/cm2 to find out if UV will degrade chlorine and monochloramine. The UV dose range for chloramine destruction and disinfection is from 40mJ/cm2 to 60mJ/cm2 in swimming pools.”

“The study concluded: “Chlorine and monochloramine in water decay steadily when exposed to monochromatic (LP) and polychromatic (MP) UV light. However, total decay of chlorine and monochloramine are relatively small in the UV dose range that is generally applied for disinfection (15-130 mJ/cm2).”

“The assumption that MP lamps burn more chlorine than LP lamps and thus are not as effective is simply misguided.”

The statements in the above five paragraphs are confusing and misleading. One has to realize that any photolysis process will require a UV dose for 90% degradation that is 10 – 50 times that for 90% inactivation of bacteria or viruses. The reason is that for a photolysis process, the quantum yield is of the order of unity or less. However, in the inactivation of bacteria and viruses, there is a multiplication mechanism. Only about 100 thymine base pairs in a DNA chain of over 1 million bases need to be ‘dimerized’ to achieve total inactivation of the microorganism. Thus alteration of only about 0.01% of the bases leads to an inactivation (inability to replicate) or the microorganism. This is why the inactivation of microorganisms is so much more effective than direct photolysis processes.


Have UV Lamp questions? Contact us at info@emperoraquatics.com. or for more information about Low-Pressure and Medium-Pressure UV Lamp differences please visit our Germicidal UV Lamp Information Page.


James A. Pantano, M.D.
of Allentown, PA

Sent to Aquatics International as shown here.


As a physician with special interest in crypto and UV denaturization of crypto DNA, I was surprised to read certain out-of-context and incomplete comments in the article by Ron George, most especially the comments related to photorepair of crypto exposed to low pressure UV.

Certainly photo repair may occur with low intensity exposure — perhaps in the 10-15j range — it is unlikely after exposure emitted by commercially available units, whether low pressure or medium pressure, in the order of 4 to 6 times this intensity. I would like to see a qualified rebuttal to this comment by some other industry expert or academic contributor, as it is the essence of the growing UV story in the aquatic world.

As an aside, the narrow spectrum emitted by LP UV is a distant absorption wavelength than free chlorine and is less likely to destroy free chlorine than the wide spectrum of MP UV — again a matter of degree that was minimized by the author.

The article smacks of commercialism and half statements rather than an impartial review of the subject. I was also amused by the pairing of this article with a prominent ad by a manufacturer of low pressure units. Was that supposed to be a joke? If it was, it worked — I smiled.


Have UV Lamp questions? Contact us at info@emperoraquatics.com. or for more information about Low-Pressure and Medium-Pressure UV Lamp differences please visit our Germicidal UV Lamp Information Page.


"Pressure Situation" Response Article
by Dan Dycha of Emperor Aquatics, Inc.

Sent to Aquatics International
editor Gary Thill on June 10th 2010
also shown here.


The Tech Talk article “Pressure Situation” by Ron George (Engineered Treatment Systems, LLC) presented in the Aquatics International May 2010 issue appears to be a biased advertisement instead of an informative resource, based on factual technology.


My name is Dan Dycha; I am the National/International Swim-Fountain Account Manager for Emperor Aquatics, Inc. (Pottstown, Pennsylvania) and I find the information Mr. George reveals in his “Pressure Situation” article to be vague and unsubstantiated. In said article he essentially promotes his company’s (ETS) Medium-Pressure UV systems while discounting competing Low-Pressure UV systems. I believe Mr. George’s article is filled with biased opinions, accompanied by minimal technical fact, and, as a result, is a disservice to the commercial swim community.

Please allow me to explain.

I agree that UV, for Aquatics, is a youthful segment that has grown exponentially in the past 5-10 years. But that is exactly why it is relevant to look at the more mature segments using this technology, such as the drinking water and waste water treatment industries, and benefit from their 30+ years of research, regulation, and hands on experience.

My rebuttal to Mr. George’s article concerns his blatant misrepresentation of Low-Pressure technology. From a spectral output perspective, the four charts displayed demonstrate the distinct differences between Low-Pressure (LP) and Medium-Pressure (MP) lamp technologies. These charts reveal the spectral output of both lamp technologies and how they relate to the spectral absorption of Chloramines and Free-Chlorine. Charts A and B specifically reveal the spectral output of both technologies within the Germicidal Disinfection Curve. In Mr. George’s article, he fails to address critical Medium-Pressure performance characteristics that include: low conversion of input watts to UV-C output watts (causing high electricity consumption), excessive operating temperature, and Free-Chlorine absorption.

Low-Pressure UV Lamps Chart A         (click the chart image for a large view)
Low-Pressure UV Lamps Chart A

Medium-Pressure UV Lamps Chart B         (click the chart image for a large view)
Medium-Pressure UV Lamps Chart B

Many of you are pool operators and know, as an accepted fact, that sunlight greatly increases Free-Chlorine absorption in your outdoor pools. If you look at the power distribution of the spectral output for Medium-Pressure systems, you will see that most of this lies within the visible light range, which is why many facilities actually increase their chlorine expenditure after installing a Medium-Pressure UV system. This may also explain why Mr. George downplays the role of Free-Chlorine consumption with the use of Medium-Pressure systems. This consumption rate is particularly exemplified in applications such as spray parks or spa applications where the turnover rate is typically from ½ hour to 45 minutes, which can add up to dozens of passes per day.

The comment, from the study in Mr. George’s article, regarding Low-Pressure systems’ vulnerability to photorepair, was also misstated. This study showed photorepair for both Medium-Pressure and Low-Pressure UV systems with low applied doses, between 5mJ/cm2 - 20mJ/cm2. Mr. George conveniently forgot to add the results from the study which state: “With well maintained UV reactors delivering appropriate UV doses of 40mj/cm2 or greater, followed by suitable chemical disinfection it is unlikely that opportunity for photorepair of E. Coli O157:H7 of significance to affect public health would arise following either low pressure or medium pressure UV irradiation.” It is for this very reason why 40mj/cm2 or greater is the universal standard for not only Aquatics applications, but drinking water and waste water applications as well. I worked directly with the State of New York for the Seneca Lake State Park application on the specification and validation of the UV system that was installed there, which is a Low-Pressure UV system. Given the high profile of the situation, anything less than the best protection for their park would have been unacceptable.

In Mr. George’s article, he attacks Low-Pressure technology’s ability to destroy Chloramines, which is a completely erroneous statement. The fact is, Low-Pressure lamps, with their narrow spectral output, are quite effective at destroying Mono-Chloramines (see chart C). Our position regarding this topic is quite simple; destroying Mono-Chloramines does not allow for the creation of Di and Tri-Chloramines. Mr. George touts his Medium-Pressure systems’ ability at destroying Di and Tri-Chloramines, which is true. Unfortunately for the swim community, he fails to reveal that the same spectral output absorbed by Di-Chloramines is also absorbed by Free-Chlorine (chart D).

Low-Pressure UV Lamps Chart C         (click the chart image for a large view)
Low-Pressure UV Lamps Chart C

Medium-Pressure UV Lamps Chart D         (click the chart image for a large view)
Medium-Pressure UV Lamps Chart D

Mr. George goes on to attack Low-Pressure technology’s operating efficiency based on temperature (68°F). Either Mr. George is unaware or he is intentionally failing to reveal that there are in fact three styles of Low-Pressure UV lamps. And Amalgam lamps, which offer the highest output, incidentally, are not sensitive to the temperatures associated with swim-spa applications. The facts state that Low-Pressure UV systems, when compared to Medium-Pressure UV systems and when applied to recreational swim applications, operate more efficiently, cost significantly less, and deliver a far less cost of ownership. From an electrical consumption standpoint, Low-Pressure lamps consume a fraction of electricity when compared to Medium-Pressure, hence providing a truly GREEN solution.

In regards to UV lamp history, Mr. George would like you to believe that Medium-Pressure lamps were developed for the Swim market, but the facts show they were originally developed and designed for the drinking water and waste water treatment industries. Years later, UV lamp technology has advanced, as mentioned previously, to offer three styles of Low-Pressure lamps, each with its own advantages (output -vs. cost).

Twenty years ago Low-Pressure “standard output” lamps were highly effective, but systems for many municipalities often required literally hundreds, sometimes thousands, of lamps. Back then, Medium-Pressure technology, while not as efficient (UV-C output & useful life) and cost effective from an electrical consumption perspective, did require fewer lamps. As you can imagine from an operational (labor) “cost” standpoint, facilities/municipalities took notice to the labor associated with changing out all of those lamps. But that was years ago. If you do a web search using “Medium-Pressure UV lamps” your search will reveal the market in which many of these lamps are typically used…paint, ink and adhesive curing—and rightfully so, their broad spectral output is suited for these applications. Today, again as a result of advancements in Low-Pressure technology, many facilities/municipalities are taking advantage of the efficient, cost saving Amalgam UV lamp. Given that the average municipal UV system costs anywhere from hundreds of thousands of dollars to millions of dollars, and is the most regulated segment in the industry by the EPA, Federal and local governments, you can bet that they perform efficacy tests and cost analysis from every angle. That being said, the technology used is overwhelmingly Low-Pressure. I should know; I supply many of these facilities with Low-Pressure Amalgam lamps.

Mr. George does however offer up some valuable advice in his article when he recommends that buyers of UV systems request references from the pool operators themselves. One such Low-Pressure UV system reference is Mr. Duane Moses who manages the Freedom Valley YMCA (Spring Valley Pennsylvania Branch). Mr. Moses painstakingly tracked his Chlorine usage after the installation of three Low-Pressure UV systems and was pleasantly surprised when he learned of an annual Chlorine savings of $3,288.00. He was also as surprised to find that his Chloramines dropped to “zero”. Mr. Moses’ dedication, regarding the tracking of his Chlorine usage-expense and Chloramines, should not go unnoticed and should serve as an example to other facility managers and operators. Testing and tracking water quality conditions and the associated expenses is very important.

Much has changed in the swim community over the past twenty-years, especially attitudes towards Chlorine. Twenty years ago suppliers were hell-bent on selling as much Chlorine as possible. But the public became disenchanted with skin/eye irritation and the EPA identified it as a carcinogen. Additionally, increased Cryptosporidium outbreaks are occurring; intensifying the community’s awareness and interest in UV. Within the past 5 years the learning curve of UV has gone up considerably, yet only 5%-10% of the pools in the entire country incorporate UV into their facilities. Thanks in part to the findings of the CDC, we are aware that most Crypto outbreaks have occurred in chlorinated pools, and that it can take chlorine up to 10 days to inactivate Cryptosporidium, while a properly designed UV system, applied correctly will treat it instantaneously. This is a fact, yet the reason that UV is only used in such a small percentage of swim facilities, is that UV is viewed by many facility managers as a luxury and not a necessity (based on the capital cost and cost of ownership of predominantly Medium-Pressure UV systems.)

From a cost perspective, Low-Pressure UV systems pose a serious threat to less efficient, more expensive Medium-Pressure systems and Mr. George (ETS) is well aware of this...hence his article. Once the Aquatic market matures as the other segments have, the debates and arguments regarding this technology will subside, and Medium-Pressure technology will lose its foothold in yet another market segment. For those of you that would like more information regarding lamp technology please visit: www.emperoraquatics-pool.com or contact me at 704-910-0827.

In conclusion, if you are interested in the truth, and are looking for unbiased information, seek out your Aquatics Professional and Facility Operator peers who are utilizing UV Systems, but most importantly, also tracking the water quality, UV system cost of ownership, Chloramine levels and Chlorine usage. Call facilities that use both LP and MP technologies, compare their notes and then make your own decisions based on performance, initial capital costs, 3-5 year maintenance costs, as well as the operational costs including electricity consumption.

Have UV Lamp questions? Contact us at info@emperoraquatics.com. or for more information about Low-Pressure and Medium-Pressure UV Lamp differences please visit our Germicidal UV Lamp Information Page.

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