pH & Alkalinity ~ Expert Pool & Spa, Inc.

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Water Parameters for Ph and Total Alkalinity:

	pH - Ideal range is 7.4 to 7.6
	Total Alkalinity - Ideal range is 80-100 ppm.

pH:

The pH is a measure of the active acidity in pool or spa water. Technically it is a measure of the concentration of hydrogen ions in the water. The greater the concentration of active hydrogen ions, the lower the pH.

On the pH scale from 0 to 14, 7.0 is neutral, less than 7.0 is acidic and above 7.0 is basic (or alkaline). The range of acceptable pH level in a pool or spa is from 7.2 to 7.8, but the ideal range is 7.4 to 7.6.

When the pH approaches or goes below 7.2, the water becomes corrosive, damaging vinyl and plaster surfaces as well as pipes and other equipment. Low pH can also result in eye irritation for the swimmer.

When the pH goes above 7.6, chlorine disinfectants are less effective in killing bacteria and algae. The water can become cloudy and scale can form on the equipment, in sand filters and on the pool walls. High pH can cause itchy skin and eye discomfort.

	When pH is too high, add acid - Acid combines with water, increases the hydrogen ion concentration, and lowers the pH. Muriatic acid (dilute hydrochloric acid - 20º Baume) or Sodium Bisulfate (Dry Acid) are commonly used to lower the pH. Always follow the label for instruction on adding acid.
	When pH is too low, add Sodium Carbonate (Soda Ash) - This is not the same as Sodium Bicarbonate (Baking Soda). The carbonate ions from sodium carbonate combine with hydrogen ions to reduce the hydrogen ion concentration. Sodium Carbonate is available in granular form.

Total Alkalinity:

Total Alkalinity is a measure of the "buffering capacity" of water, or its ability to resist a change in pH.

The ideal Total Alkalinity level for pool or spa water is 80 - 120 ppm. When the Total Alkalinity is too low, the pH level can fluctuate widely and the water can become corrosive. When the Total Alkalinity is too high, the pH will be high and scale will form on pool surfaces and equipment.

	To lower Total Alkalinity, add Acid - The acid reacts with bicarbonates in the water and converts them, reducing the Total Alkalinity. Add 1.6 pounds of Dry Acid (Sodium Bisulfate) per 10,000 gallons of water, or 1.3 quarts of Muriatic Acid, to decrease the Total Alkalinity by 10 ppm. Retest and adjust the pH.
	To raise Total Alkalinity, add Sodium Bicarbonate - This adds to the total bicarbonates in the water, raising the Total Alkalinity. Add 1.5 lbs. Sodium Bicarbonate per 10,000 gallons of water to increase the Total Alkalinity by 10 ppm.

Remember, Total Alkalinity and pH level are closely related, so it is important to test pH after adjusting Total Alkalinity. Likewise, a proper Total Alkalinity level is important in maintaining the recommended pH level. It may take several sodium bicarbonate treatments to build the proper Total Alkalinity buffering level to keep the pH in the proper range.

To Increase Alkalinity using Sodium Bicarbonate

VOLUME OF WATER
Desired increase in ppm	400 Gallons	1000 Gallons	5000 Gallons	10,000 Gallons	20,000 Gallons	50,000 Gallons	100,000 Gallons
10 ppm	0.90 oz	2.24 oz	11.20 oz	1.40 lbs	2.80 lbs	7.00 lbs	14.0 lbs
20 ppm	1.79 oz	4.48 oz	1.40 lbs	2.80 lbs	5.60 lbs	14.0 lbs	28.0 lbs
30 ppm	2.69 oz	6.72 oz	2.10 lbs	4.20 lbs	8.41 lbs	21.0 lbs	42.0 lbs
40 ppm	3.59 oz	8.97 oz	2.80 lbs	5.60 lbs	11.2 lbs	28.0 lbs	56.0 lbs
50 ppm	4.48 oz	11.2 oz	3.50 lbs	7.00 lbs	14.0 lbs	35.0 lbs	70.0 lbs
60 ppm	5.38 oz	13.4 oz	4.20 lbs	8.41 lbs	16.8 lbs	42.0 lbs	84.1 lbs
70 ppm	6.28 oz	15.7 oz	4.90 lbs	9.81 lbs	19.6 lbs	49.0 lbs	98.1 lbs
80 ppm	7.17 oz	1.12 lbs	5.60 lbs	11.2 lbs	22.4 lbs	56.0 lbs	112.0 lbs
90 ppm	8.07 oz	1.26 lbs	6.30 lbs	12.6 lbs	25.2 lbs	63.0 lbs	126.0 lbs
100 ppm	8.97 oz	1.40 lbs	7.00 lbs	14.0 lbs	28.0 lbs	70.0 lbs	140.0lbs

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This website was last updated on
Friday February 22, 2008