Regarding cooling towers, the water temperature for pH testing should be between what degrees Fahrenheit?

• A. 60-70
• B. 80-90
• C. 90-100
• D. 70-80

Answer: (D)

pH readings in cooling tower water are affected by temperature, so you want to test at a moderate, representative temperature rather than at extremes. About 70–80°F keeps the sample in a range where the carbonate system and CO2 exchange are closer to what the circulating water experiences, so the measured pH reflects the actual operating conditions. If the water is warmer, CO2 tends to degas and pH can rise; if it’s cooler, more CO2 stays dissolved and pH can be lower. Testing in this mid-range also aligns better with typical calibration and temperature-compensated readings, giving a more reliable basis for dosing. Choosing a temperature outside 70–80°F increases the chance that the pH measurement won’t match the tower’s real operating chemistry.