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Why Do My Eyes Sting?
Red irritated eyes, sometimes in conjunction with dry,
itchy skin, are an occasional occurrence in some swimming pools. There are a
number of possible explanations for the irritation when it occurs, some of which
are actual causative factors and some of which are popular misconceptions.
The most popular misconception about eye irritation is that it is
caused by excess chlorine. The most common actual causes of eye irritation are
pH imbalance, chloramine buildup, high dissolved solids, or a combination of
those factors.
Low pH
One cause of eye irritation is low pH. Since the eyes are
protected by fluid (tears), the altering of the chemistry of that fluid affects
the eyes. An example of using this principle is the use of alkaline eye drops
to ease tired, irritated eyes. Eye irritation caused by low (acidic) pH can be
remedied by proper balancing the alkalinity and pH levels in the pool. Low pH
can also cause irritation to the ears, nose, throat, and other mucous membranes,
as well as being detrimental to the components of the pool itself.
Chloramine
Chloramine is a chemical combination of ammonia and chlorine. While
chlorine is a desired component in pools, ammonia is unnecessary and unwanted.
In pools, ammonia comes from sweat, spit, urine, bird droppings, dog waste, lawn
and garden fertilizers and some chemical algaecides. Chloramine is an irritant
to your eyes, skin, and other parts of the body. The chlorine in chloramine
loses its sanitizing power and has a distinctive "rotten chlorine"
odor.
Another characteristic of chloramine is that it changes in
composition relative to the pH of the water. The lower the pH, the more of an
irritant the chlorine becomes. Since low pH in and of itself can be an
irritant, low pH in conjunction with chloramine is even worse.
The cure for chloramine is to add enough of an additional oxidizer to
burn out the ammonia. This process can be accomplished with more chlorine -
roughly 7 to 10 times as much chlorine as ammonia. This is referred to as
superchlorination, or breakpoint chlorination (the addition of chlorine to the
point that it breaks the chloramine bond and destroys the ammonia).
Alternatively, non-chlorine oxidizers such as oxygen-based shock chemicals, such
as potassium peroxymonosulfate or monopotassium persulfate, may be used.
Total Dissolved Solids (TDS)
A third causative factor for eye irritation in swimming pools
can be a high level of dissolved material in the water. An acceptable amount of
total dissolved solids (TDS) may be as low as a few
hundred parts per million (ppm) and as high as 2000-3000 ppm. When levels
exceed 3000, the results may include eye irritation, cloudy water, and
difficulties in maintaining water balance. Meters are commonly used to measure
the TDS of a pool, but a do-it-yourself test is to simply open your eyes
underwater. Pool water with excess TDS may be crystal clear when looking at the
water from above, but when you open your eyes underwater, it is normally turbid
(cloudy or hazy). If you suspect high TDS, call Thunderbird Pool for testing of
your water.
Conclusion
Eye irritation, whether caused by pH, chloramine, TDS or some combination
of factors is both preventable and curable. Although extended swimming may
irritate eyes, irritation that occurs after only short periods of swimming needs
to be investigated and remedied. If you are experience such irritation, please
give us a call. |
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