Fill the test vessel to the 20mll mark with cooled sample water Add 10 drops of reagent TH-2 (Total hardness Buffer) to the test vessel and swirl gently to mixAdd one scoop of reagent TH-1p(total hardness indicator) to the same test vessel Swirl gently to dissolve the powder. If the sample colour appears a little weak, add more TH-1 to obtain a stronger colour. Add reagent Th-3 ( hardness low range titration ), one drop at time, gently swirling the test vessel after each addition. Count how many drops are required for the sample to change the sample from wine red to pure blue. Note the number of drops added.Calcium hardness procedure Carry out the test as for total hardness above, except substitute CH-2( calcium Hardness Buffer) for TH-2 (total hardness buffer) in sep 2 and CH-1p (calcium Hardness Indicator for TH-1p( Total hardness indicator) in step 3. Total hardness ppm( as caco3 ) = Number of drops of TH-3 used *1 Calcium hardness ppm( as caco3) = Number of drops of TH-3 used *1Note: For a 10ml sample , multiply the number of drops of TH-3 used by 2 to give ppm hardness ( as CaCO3)Note: this test uses dropper bottles that deliver a calibrated drop size. It is important to hold all dropper bottles exactly upside down when dispensing reagent.Allow drops to fall off under their own weight or by very gently squeezing the bottle. Failure to dispense reagent in this manor will affect drop size and ultimately test accuracyLow range and high range titration test
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