LaMotte Pool Manager Water Quality Handbook - Manual (Page 18)

How do we test Alkalinity?
The level of alkalinity is usually determined using a
titration method: an indicator is added to a water
sample to produce a distinct color. A weak acid (titrant)
is then added slowly until the original color changes.
The amount of titrant added to produce the color
change determines the result, either by counting the
number of drops added or by measuring the volume of
titrant. Read the test instruction carefully to determine
the proper color change and procedure required. If there
is ever doubt in the test result, repeat the test and
carefully stop the titration procedure when the endpoint
color is reached.
Ideal Ranges for Alkalinity
80 - 100 ppm
• In pools using calcium hypochlorite or
sodium hypochlorite
100 - 120 ppm
• In pools using dichlor, trichlor, chlorine gas
or bromine
Note: Cyanuric acid contributes to the alkalinity test. The
alkalinity reading should be adjusted to compensate for this. Do
this by multiplying the cyanuric acid reading by 1/3 and
subtracting this from the alkalinity reading.
CYA = 60 ppm
TA = 100 ppm
100 - (60 x 1/3) = 100 - 20 = 80
Thus 80 ppm is the true carbonate alkalinity value that should
be used in water balance calculations.
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