By now, many aquatics professionals
have heard about the benefits of ultraviolet technology for
reducing chloramines, especially on indoor pools. But many of these
same professionals may not realize there are two distinct types of
UV lamps — and that understanding the difference between the
two can potentially save thousands.
seems aquatics professionals have so far ignored the most common,
and inexpensive, type of industrial UV technology. That type of
system is called amalgam, or low-pressure/high-output
uses low-pressure UV lamps that are very similar to common
fluorescent lamps. Both contain a small amount of mercury. The UV
lamp tube is made of quartz, not glass. Quartz allows UV energy to
pass through, while glass does not. These lamps emit UV energy at
one specific wavelength, which is beneficial for chloramine control
and disinfection. In the 1990s, low-pressure lamps were enhanced by
altering the makeup within the lamp. The result was an amalgam lamp
that could replace three common low-pressure lamps. Except for
small applications, amalgam UV has become the most popular
technology for the majority of industrial
The other type
of UV technology — medium pressure — is more expensive
and more common in the aquatics industry. Medium-pressure lamps are
designed to receive as much as 20 times the electrical power of a
low-pressure lamp. The higher level of energy results in an output
at every wavelength within the UV range.
amalgam (low-pressure/high-output) technology seems to offer
several advantages over medium pressure
systems emit wavelengths of 254 nanometers, which is very close to
the optimum wavelength needed for disinfection and chloramine
control. In fact, a recent Duke University study concluded that
amalgam systems are more effective at degrading monochloramines
than medium pressure. The same study also showed that
medium-pressure systems actually destroy more free chlorine than
- Amalgam lamps are nearly three times more energy-efficient.
That means amalgam UV offers significantly lower electrical
- Amalgam lamps can last longer. Medium-pressure lamps are
rated for up to 5,000 hours of life; amalgam lamps are rated for up
to 12,000 hours.
- Amalgam systems have redundancy designed into the system.
That means they typically contain three to six lamps, while medium
pressure use only one. If an amalgam lamp is defective, the other
lamps will continue to carry most of the load. There is, therefore,
no loss of protection.
- Lamp temperatures do not require special controls for
amalgam systems. Medium-pressure lamps operate at temperatures
exceeding 1,500 degrees Fahrenheit. It is important to make sure
the pumps are operational when the lamp is on. The surface
temperature of amalgam lamps, on the other hand, is approximately
250 degrees Fahrenheit, and overheating is not a serious
In almost every aquatic situation, it is less expensive to own and
operate an amalgam UV system when compared with a medium-pressure
system. The area where medium pressure may make more sense from a
cost standpoint is when there are extremely high flow rates, such
as a large outdoor waterpark. For chloramine control, a cost/
benefit analysis should be performed around 4,000 gpm.
which system you choose, UV is a reliable, inexpensive and
effective way to deal with chloramines.
aquatics facilities with UV systems will provide healthier
environments for patrons and staffs. The question to be asked is
not whether to use UV on an indoor pool; it should be which type is