pH

pH is the measure of relative acidity or basicity of pool water. It is the single most important factor in swimming pool water chemistry. It affects every other chemical balance in pool water.

pH is measured on a scale of 0 (strong acid) to 14 (strong base) with 7 being the neutral pH.

In pools, a pH of 7.4 to 7.6, slightly above neutral, is most desirable because this range is most comfortable to the human eye and skin.

If pH is too low (below 7.2)

• water becomes acidic
• chlorine fades rapidly
• eye irritation occurs
• concrete, gunite, or plaster walls are etched
• pump, and heater parts, and other metal fittings may corrode
• dissolved metals may leave stains on walls

If pH is too high (above 7.8)

• chlorine activity is slowed and inefficient
• scale formation and discoloration on pool walls
• water can become cloudy
• filter becomes overworked
• eye irritation may occur

pH Adjustment

To avoid the problems listed above, pH must be maintained between 7.2 and 7.8. The most desirable level for pH is between 7.4 and 7.6.

• If pH is too low, use Robelle pH Rise.
• If pH is too high, use Robelle pH Lower