LaMotte Pool Manager Water Quality Handbook - Manual (Page 29)

How do we test Cyanuric Acid?
Test results are determined by the degree of cloudiness or
turbidity that develops when a test reagent is reacted
with cyanuric acid. The amount of turbidity indicates
the level of cyanuric acid, with low readings being more
transparent and high readings being very cloudy.
The cyanuric acid test is usually made by viewing the
reacted test sample in a special reading tube containing
a black dot on the bottom. The reacted sample is
dispensed into the tube to a point where the black dot
disappears from sight. At this point the depth of the
solution indicates the cyanuric acid concentration. In
most test kits the values for concentration in ppm are
displayed on the side of the tube.
The analyst should always keep in mind that cold or hot
water samples will interfere with the test results. It is best
to test samples between 70°-85°F.
Ideal Range for Cyanuric Acid
30 - 50 ppm (maximum level 100 ppm)
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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