Balancing pH

In a hot tub, pH balance is very important. Low pH can damage surfaces and equipment and can cause eye and skin irritation, while high pH can cause scale buildup and cloudy water. Proper pH balance is also necessary for the sanitizer to work the most efficiently. But, it is often difficult to maintain pH in the ideal 7.4 – 7.6 range.

Test the pH twice a week and adjust as needed.

High pH

Many things about a spa cause the pH to stay or appear high. pH is naturally raised by warm water (obviously common in spas), other products, foreign substances and bathers (also common in spas). Aeration is also a culprit – it releases carbon dioxide from the water, which in turn reduces the amount of carbonic acid present in the spa. This causes pH to increase. (To lessen the effects of pH drift, add chemical products with the aeration off.) Use Spa pH Decreaser to lower pH.

CAUTION: A common mistake that is made with pH in spas is to diagnose it as high when it is actually low. In brominated spas, the brominating product reacts with the phenol red reagent to make the pH reading look purple. This discoloration is exaggerated when the pH is already low. Use up to 5 drops of chlorine neutralizer to make sure that you are getting accurate pH readings when testing with phenol red.

Low pH

Low pH is usually attributable to low Total Alkalinity and/or use of Brominating tablets. (Note: Trichloro chlorinating tablets are not recommended in spas because of the potential for surface damage.) Brominating tablets can cause the pH and the total alkalinity to drift down rapidly. If these products are being used, check pH frequently to avoid equipment damage. As indicated above, use up to 5 drops of chlorine neutralizer to make sure that you are getting an accurate pH reading if you are testing with phenol red. Use Spa pH Increaser to raise pH.

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Note: This information is intended for a residential spa with average use.  It is not designed for public, commercial, or semi-public spas.  If your hot tub is used more than three times per week, you should check and make chemical additions more often than suggested.