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Pool Water pH: FAQ

Q: What is pH?

A: pH (or potential Hydrogen) is a measure of the active acidity in pool or spa water. It refers to the amount of acid and alkaline contained inside of the 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.

Q: What is the ideal pH range for pool water?

A: 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.

Q: What happens when pool water pH is too low?

A: 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.

Q: What happens when pool water pH is too high?

A: 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.

Q: How do I lower pool water pH?

A: 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 - 20° Baume) or Sodium Bisulfate (Dry Acid) are commonly used to lower the pH. Always follow the label for instruction on adding acid.

Q: How do I raise pool water pH?

A: 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.

Q: What is alkalinity and what does it have to do with pH?

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

Q: What should the alkalinity in my pool water be?

A: The ideal total alkalinity level for pool or spa water is 80 - 120 ppm.

Q: What if my pool water alkalinity is too low?

A: When the total alkalinity is too low, the pH level can fluctuate widely and the water can become corrosive.

Q: What if my pool water alkalinity is too high?

A: When the total alkalinity is too high, the pH will be high and scale will form on pool surfaces and equipment.

Q: How do I lower alkalinity in my pool water?

A: 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.

Q: How do I raise alkalinity in my pool water?

A: 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.

Q: How do alkalinity and pH affect one another?

A: 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.

*All advice is to be used at your own risk. The Owner of this company, anyone associated with this company and web service provider do not assume any responsibility if damage/injury to your pool or yourself occurs. If you are unfamiliar with your pool, please contact a pool service technician professional.