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.

— James A. Pantano, M.D.
Allentown, Pa.

The comment, from the study in the article, regarding LP systems’ vulnerability to photorepair, was also misstated. This study showed photorepair for both MP and LP UV systems with low applied doses, between 5mJ/cm2 - 20mJ/cm2. 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 LP UV system. Given the high profile of the situation, anything less than the best protection for their park would have been unacceptable.

George attacks LP technology’s ability to destroy chloramines, which is a completely erroneous statement. The fact is, LP 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. George touts his MP 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).

George goes on to attack LP technology’s operating efficiency based on temperature (68°F). Either he is unaware or intentionally failing to reveal that there are in fact three styles of LP 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 LP UV systems, when compared to MP 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, LP lamps consume a fraction of electricity when compared to MP, hence providing a truly GREEN solution.

In regards to UV lamp history, George would like you to believe that MP 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 LP lamps, each with its own advantages (output vs. cost).

Twenty years ago LP “standard output” lamps were highly effective, but systems for many municipalities often required literally hundreds, sometimes thousands, of lamps. Back then, MP 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 LP 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 LP. I should know; I supply many of these facilities with LP amalgam lamps.

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 LP UV system reference is Duane Moses who manages the Freedom Valley YMCA (Spring Valley Pennsylvania Branch). Moses painstakingly tracked his chlorine usage after the installation of three LP UV systems and was pleasantly surprised when he learned of an annual chlorine savings of $3,288. He was also as surprised to find that his chloramines dropped to “zero.” 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 20 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 MP UV systems.)

From a cost perspective, LP UV systems pose a serious threat to less efficient, more expensive MP systems and 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 MP 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.

— Dan Dycha, national/international swim-fountain account manager
Emperor Aquatics Inc.
Pottstown, Pa.