LaMotte DPC-52 Water Testing Laboratory - Manual (Page 14)

ACID DEMAND ADJUSTMENT
In 10,000 gallons of water . . .
1
a lbs. of Sodium Bicarbonate increases the Total Alkalinity 10 ppm.
1 pt. of Muriatic Acid (Hydrochloric Acid 31%) reduces the Total Alkalinity 6 ppm.
2
b lbs. of Sodium Bisulfate (dry powder) reduces the Total Alkalinity 10 ppm.
NOTE: Always consult manufacturer’s recommendations regarding maximum amount
of acid to be added to pool at one time.
Example A: A round spa with a diameter of 8.5’ and average depth of 3.0’ gives an
alkalinity test result of 205 ppm CaCO
3
.
1. Calculate volume of water (see p. 13):
8.5’ x 8.5’ x 3.0’ x 5.9 = 1279 gallons
2. On the 205 ppm line in the Acid Demand Index above, read this volume as:
1000 + 100 + 100 + 100
3. Index Reading = 2.0 + 0.2 + 0.2 + 0.2 = 2.6 pints
4. 2.6 pints x 1.4 = 3.6 lbs Dry Acid
Example B: A rectangular pool measures 20’ x 40’ with an average depth of 5’ and gives
an alkalinity test result of 170 ppm CaCO
3
.
1. Calculate volume of water (see p. 13):
40’ x 20’ x 5’ x 7.5 = 30,000 gallons
2. In the Alkalinity Index, read this volume as:
10,000 + 20,000
3. Index Reading = 11 + 23 = 34 pints Muriatic Acid
4. 34 pints ÷ 8 = 4.25 gallons x 11.2 = 47.6 lbs (see Note above.)
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