Which of the following is a required item for pool maintenance?

A chemical test kit is essential for pool maintenance as it allows the pool operator to accurately measure the chemical levels in the water, including pH, chlorine, alkalinity, and other important parameters. Maintaining the correct chemical balance is critical for ensuring the safety and comfort of swimmers, preventing algae growth, and prolonging the life of the pool equipment. Regular testing helps in promptly identifying any imbalances that could lead to water quality issues, making it a fundamental tool for any certified pool operator.

While a first aid kit, lifesaving equipment, and a pool cover are important for safety and operational management, they do not directly pertain to the regular maintenance of water chemistry, which is crucial for effective pool operation.