LaMotte AM-21 Water Pollution Detection Outfit - Manual (Page 14)

Field Test Method—Calcium Hardness
Procedure
1. Fill the test tube (0769) to the 12.9 ml line with the sample water.
2. Add six drops of *Sodium Hydroxide Reagent with Metal Inhibitors
(4259).
3. Add one Calcium Hardness Indicator Tablet (5250). Cap and mix until
tablet is disintegrated. A red color will appear if calcium is present.
4. Hardness Reagent #7 (4487) is added as described in the Field Test
Method for Total Hardness, until the red color changes to blue. The
results are read as Calcium Hardness in ppm CaCO
3
.
5. The Magnesium Hardness level is determined by subtracting the
Calcium Hardness level from the Total Hardness level.
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