(Note from Pool Emporium, Inc.: As the full text of this material was intended
for dealers, some of it has been edited for content, and paraphrased for more effective communication to you, the
While the professionals in the swimming pool industry are familiar with the term "chlorine demand," we
are not the only industry which recognizes this situation. In Chemistry of Water Treatment, Faust and Aly quote
from Standard Methods a definition of chlorine demand as the quantity of chlorine reduced or converted "to
inert or less active forms of chlorine by substances in the water." Faust and Aly go on to add, "Since
chlorine is a non-selective oxidant, almost any substance in the water in a reduced valence state will react and
We see evidence of consumption of large quantities of chlorine in swimming pools. During the 1992 season, the Technical
Services Department of BioLab, Inc. gathered a great deal of data on chlorine demand, success of various treatment
methods and correlation of chlorine demand to ammonia in the water. The 1995 season had begun with indications
that chlorine demand is possibly even more widespread than in 1992.
For several seasons a phenomena has occurred with some swimming pools. These pools appear "typical" at
opening. After initial start up chemicals are added, the follow-up check on sanitizer residual reveals no sanitizer
in the water. Repeated additions of shocking compounds do not seem to provide the ability to maintain a residual.
Despite the absence of an active sanitizer residual, the pool is clear.
A singular cause for chlorine demand has not been determined. BioLab has learned that:
Enter The Chlorine Demand Test Station - Without it, determining the quantity of chlorine needed to satisfy the
demand for a pool is a hit or miss proposition. By using the Chlorine Demand Test Station, we are able to accurately
determine how much shock needs to be added to overcome the various components in the water which cause rapid consumption
of the chlorine.
Note from Pool Emporium, Inc.: Think of Chlorine Demand this way: When
your chlorine level drops, it doesn't stop at zero. Just like the outdoor temperature, it can fall below zero,
creating a demand. The chlorine must be brought back UP to zero before a residual can be established. The problem
will persist until the proper amount of chlorine is added to meet that demand and provide the residual.
We've included this section on Chlorine Demand to educate you on some of the possible problems that you face as
a pool owner. Trying to fight a chlorine demand is undoubtedly one of the more frustrating ones. Ignoring a chlorine
demand can lead to other problems, which are really just progressive symptoms of the chlorine demand. You must
treat the problem, not just the symptoms.
Pool Emporium, Inc. is one of the only (if not THE only) pool company in our area to have and utilize a Chlorine
Demand Test Station. Aside from the additional costs to us, each test is time consuming. It takes approximately
30 minutes over an 8 to 36 hour time span. However, we are happy to perform this test for our valued patrons. By
using our BioGuard® Chlorine Demand Test Station, we have been able to save our customers much time, additional
expense, and frustration. Just one more reason Why Pool Emporium Is Your Best Bet!
The information on this page has been provided courtesy of BioLab,
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