Which of the following describes a standard for pool water chemical levels?

• A. Free available chlorine for pools is 1.0-4.0 mg/L
• B. pH 7.2-7.8
• C. FAC for spas 2.0-5.0
• D. pH 8.0-9.0

Answer: (A)

Maintaining a defined disinfectant residual is the primary standard for pool water chemical levels. The free available chlorine should be kept in the range of about 1.0 to 4.0 mg/L. This range ensures there is enough chlorine present to inactivate pathogens that could be in the water, providing effective disinfection, while avoiding excessive chlorine that can irritate eyes and skin or cause other problems.

The other options point to related but different standards: chlorine for spas is typically higher (2.0–5.0 mg/L) because spa water is used differently and is more concentrated, so it isn’t the standard used for pools. A pH range is also important for pool comfort and chlorine efficiency, but the specific pH given as 8.0–9.0 is too alkaline for safe and effective pool operation, and a pH around 7.2–7.8 is generally preferred.