1. The alkalinity of a 90,000 gallon pool is at 50 ppm. How much sodium bicarbonate will it take to raise the alkalinity to 100 ppm?
2. The calcium hardness of a 25,000 gallon pool is at 120 ppm. How much calcium chloride (100%) will it take to raise the calcium hardness to 300 ppm?
3. The pH of a 150,000 gallon pool is at 8.2. How much sodium bisulfate will it take to lower the pH to 7.6?
The alkalinity of a 60,000 gallon pool is at 150 ppm. How much sodium bisulfate will it take to lower the alkalinity to 100 ppm?
STEP 1: Adjustment. The adjustment is the difference between what levels you’re at and the level you want to be at. (In our example, we are at 150 ppm and want to get to 100 ppm. Therefore, our adjustment is 50 ppm: (150-100))
STEP 2: Amount of Chemical. The amount of chemical is taken from the “Dosages Required” Chart for the chemical you are using. In our example, we are using sodium bisulfate to decrease our alkalinity. Therefore, our amount is 2.1 Lbs.
STEP 3: ppm in Bold. The ppm in Bold is taken from the ‘Dosages Required’ Chart just above the chemical you are using. In this case, the ppm in Bold is 10 ppm.
STEP 4: Volume. Volume is usually given for these problems. Or see Volume problems to learn how to figure out pool’s volume. Our volume is 60,000 gallons.
STEP 5: We divide our answer for Step 1 by our answer for Step 3. 50 ÷ 10 = 5.
STEP 6: We divide our answer for Step 4 by 10,000. 60,000 ÷ 10,000 = 6.
STEP 7: We multiply Step 2 by Step 5 by Step 6. 2.1 lbs. x 5 x 6 = 63 Lbs.
ANSWER: It takes 63 Lbs of sodium bisulfate to lower the alkalinity from 150 to 100.
1. 63 Lbs. of Sodium Bicarbonate
2. 40.5 Lbs. of Calcium Chloride (100%)
3. 45 Lbs. of Sodium Bisulfate