the Air: Chloramine Control for Indoor Swimming Pools
Tom Griffiths, Ed.D.
Director of Aquatics, Penn State University
President, Aquatic Safety Research Group, LLC
the most perplexing and controversial problem facing
heavily used indoor pools today is chloramine production.
Chloramines cause obnoxious odors as well as skin, eye,
and respiratory irritation that many swimmers mistakenly
attribute to chlorine itself. When chloramine levels
become troublesome (0.3-0.5 parts per million (ppm)),
people begin to complain. And while much finger pointing
takes place, often little progress is made in correcting
the problem. Swim coaches and competitive swimmers blame
the pool operators, while pool operators in turn blame
the swimmers; pool chemists blame the ventilation systems,
whereas those in charge of air handling blame the water
who truly is to blame? And how is the problem fixed?
In reality, everyone is to blame when chloramines
are produced, and everyone has a role in controlling
them. While a heavily used pool may never be completely
chloramine free, you can greatly reduce chloramine production
through good pool management practices.
chloramines and the associated smell and irritation
are caused by a variety of factors. Despite what many
swimmers assume, the major cause of these problems is
too little free chlorine rather than too much!
"Free" chlorine, used to kill germs and help prevent
the spread of waterborne illnesses, also oxidizes natural
waste products from swimmers, including sweat, body
oil, urine and other ammonia-nitrogen compounds. If
the free chlorine levels are not sufficiently high to
oxidize these nitrogenous wastes, the free chlorine
combines with them to form noxious cholarmine compounds.
Whenever someone calls me with a chloramine problem,
the first thing I tell him or her is that once they
shock their pool (shock treatment will be discussed
below) they should maintain a free residual of 0.5ppm
higher than usual. This higher level of chlorine
usually does the trick.
remedy that is rarely used but very effective is to
enforce soap showers prior to swimming. A soap shower
will remove excess body oils and sweat, thus greatly
reducing the amount of body waste going into the pool.
Some pool chemists claim that if everyone showered prior
to swimming, it would reduce the chlorine demand by
50%. So perhaps you could get your swimmers to shower
if you told them to shower, not because they are dirty
but rather because their body oils react with chlorine
to produce the smell they hate. Along those lines, competitive
swimmers produce a great deal of sweat when they train
rigorously. There is absolutely no way to avoid this,
so you must plan on combating the perspiration that
they will normally and regularly produce.
with the cleanest swimmers and the best water chemistry,
though, chloramines can be a problem. If you have an
energy efficient air handling system that re-circulates
the air, often the chloramines are re-circulated and
trapped in the building because they cannot escape.
Air handling systems must bring in lots of fresh air
and exhaust full blast when the pool is busy. If this
is not done, chloramines will keep building. If the
air handling system does not significantly exceed existing
ASHRAE standards, then a heavily used pool will probably
have an air quality problem.
notice how you don't notice chloramine odors at an outdoor
pool? As they say, "No harm, no foul."
you have an abundance of chloramines, they are not easy
to get rid off. Just like algae growth in swimming pools,
the key is prevention. And just like "Layers of Protection"
for drowning prevention we also need "Layers of Protection"
against chloramines. To help prevent and rid
your facility of chloramines once they develop, you
may want to experiment with a combination of the following:
more often with free chlorine. Shock treatment involves
raising the free chlorine level to at least 10 times
higher than the combined chlorine level. Weekly is
best for most pools but it may be required even more
often for extremely heavily used pools.
a non-chlorine shocking agent like the monopersulfate-based
oxidizers. These reduce chloramines without adding
chlorine. Many pool operators find alternating between
traditional chlorine and the non-chlorine shocking
agents works best.
volcanic ash to your sand filters. This holds the
ammonia in the filter tanks rather than in the swimming
pools. Zeolite works well but must be regenerated
to be effective in the long run.
Activated Carbon (GAC) filters may also be added to
your existing filtration/circulation systems to remove
ammonia that produces chloramines in the pool water.
heavy bather loads. When you know your swimming pool
is going to be inundated with swimmers either by way
of a swim meet, swimming lessons or a huge rental
or party, take preventive action prior to the swimmers
the pool and keep the free chlorine levels up extra
high before the swimmers enter the pool. Insist that
the group shower before entering. These preventive
measures will do wonders in keeping chloramines formation
to a minimum.
you have a good clean source of fresh water, give
your filters and extended backwash so that you drain
off lots of water (up to 1/3 of your pool volume)
and replace it with fresh water.
and brushing your pool daily also removes much of
the dirt chlorine reacts with that your filters have
not caught yet.
word of caution -- Many water companies are using chloramines
to disinfect the water they supply their customers.
If your source water is disinfected with chloramines,
as many are, you have an uphill battle on your hands.
The facility may need to strip the chloramines with
a GAC filter as the water enters the building and before
it enters the swimming pool.
Finally, most of the "ideal" ranges recommended for
chlorine in public swimming pools are simply too low
and just plain wrong. Heavily used pools often need
3.0 - 4.0 PPM in order to prevent chloramines. Try running
yours higher for six months. You'll be glad you did.
more information, refer to Chapter 10: Superchlorination
The Complete Swimming Pool Reference, Sagamore
Publishing and www.aquaticsafetygroup.com.