LaMotte HARDNESS IN WATER 1606 - Manual (Page 6)

TAKING WATER SAMPLES
There are many factors to consider before taking a water sample.
·
The water sample should be representative of the source and free of
any foreign matter, such as aquatic plants and sediment from the
bottom.
· The container should be clean and free from particles. Use a plastic or
glass container with a screw cap that is large enough to hold water for
all desired tests.
· Unless the sample is to be tested immediately, the container should be
filled until it overflows, and then capped. This procedure eliminates
the possibility of getting air bubbles into the sample. A container
which is only half full with water is subject to chemical changes caused
by oxidation while transported. Generally, the less time between
collecting and analyzing the sample gives the best results.
· If the sample is taken from a tap, it is important to let the water run
for several minutes before the sample is taken.
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WATER HARDNESS: METHOD I
1.
Fill the test tube (0608) to the 20 mL line with sample water.
2. Add one Hardness T Tablet (6917). Shake until disintegrated. Sample
should turn red.
3. Continue adding Hardness T Tablets one at a time, shaking after each
tablet until the tablet disintegrates, and the red color changes to blue.
Count the number of tablets added.
NOTE: When counting tablets be sure to include the tablet used in
Step 2.
4. Use the following chart to determine hardness of sample.
# OF DEGREE
TABLETS OF HARDNESS RANGE
1 soft 20-100 ppm
2 hard 120-200 ppm
3 or more very hard over 200 ppm
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