SECTION 310:320-5-2. Water balance and water balance tables

(a)   Water balance is accomplished by adjusting the pH, total alkalinity, and calcium hardness in relation to each other. Tests are run on the pool water to determine the values for pH, total alkalinity, and calcium hardness. The accompanying table is used to determine scaling or corrosive potential of the water and to indicate corrective measures needed. Pools and spas that do not have balanced water are not only subject to considerable damage to the facility from scaling or corrosion but do not make effective use of free chlorine and indeed often have difficulty maintaining the required chlorine and pH levels. For more information, please contact your local health officials. Recommended values are:

(1)   pH 7.2 to 7.8

(2)   Total alkalinity 80-120 ppm (pools) 100-150 ppm (spas)

(3)   Calcium hardness 100-150 ppm (pools) 150-300 ppm (spas)

(b)   Directions to determine water balance point are as follows:

(1)   Test the pool or spa water to determine the level of pH, total alkalinity, and calcium hardness.

(2)   On the "Variable Temperature Water Balance Chart," locate the test values for total alkalinity and calcium hardness.

(3)   Connect a line between values for Total Alkalinity and Calcium Hardness. Mark the intersection with the pivot line. This becomes the pivot point. Draw a horizontal line through the pivot point and the pH scales. Read the pH from the appropriate pH-Temperature Scale at the intersection with the horizontal line. This is the pH at which the water is balanced and is neither corrosive nor scaling.

(4)   If the pool water pH value shown on the chart is no more than 0.5 pH above or below the actual observed pH in #1, above then the water is in balance.

(A)   If the actual pool water pH is 0.5 units higher than the pH value indicated in the chart, then the water is considered scaling and will deposit calcium in lines, filters, and in the pool.

(B)   If the actual pool water pH is 0.5 units lower than the pH value indicated in the chart, then the water is corrosive and will corrode the metal pipes, pump impellers, ladders, and other fixtures and will etch the pool plaster making it "sandy."

(5)   Calcium hardness is the hardest of the three to balance. Therefore, using the actual calcium hardness value as a pivot point, move the line between 7.2 and 7.8 to see at what level the total alkalinity can be adjusted to balance the water. The pH should be adjusted first to between 7.2 and 7.8 (ideal is 7.6) and then the total alkalinity adjusted last. It is perfectly permissible to operate a pool at a slightly higher or lower pH than ideal (but within the 7.2 to 7.8 range) in order to balance the water.

(6)   Cyanuric Acid vs. Total Alkalinity. Cyanuric Acid will titrate as total alkalinity using the current field tests. The following is a conversion chart that may be used to determine the corrected value to Total Alkalinity:

pH	Cyanuric Acid Factor
6.0	.04
6.5	.10	1. Test total alkalinity, pH, and Cyanuric Acid.
7.0	.21	2. Multiply ppm Cyanuric Acid by Cyanuric Acid Factor.
7.5	.30	3. Subtract the product from the measured total alkalinity.
8.0	.36	4. The result equals actual total alkalinity
8.0	.38
9.0	.38	For Example: With a pH of 7.5, Cyanuric  Acid of 50 ppm, and Total Alkalinity of  150 ppm.
		150 − (50 × .30) = Actual Total Alkalinity
		150 − 15 = 135 ppm Actual Total  Alkalinity