Which of the following methods is primarily used to check water quality in pools and spas?

Chemical analysis is primarily used to check water quality in pools and spas because it provides a precise measurement of various water chemistry parameters. This method allows for the evaluation of essential components like pH levels, sanitizer concentration (such as chlorine or bromine), total alkalinity, and calcium hardness.

By conducting chemical analysis, operators can identify imbalances or contamination in the water, which can lead to health risks or complications with pool equipment. This thorough testing is essential to maintain water safety and clarity, ensuring that the pool or spa remains a healthy environment for users.

Other methods, such as visual inspection, may help in identifying visible issues like cloudiness or algae presence but lack the quantitative accuracy necessary to assess water quality effectively. Electronic testing can also provide quick results but may not cover all aspects of water chemistry comprehensively. Filtration tests are crucial for understanding the mechanics of how water is processed but do not directly measure water quality parameters. Therefore, chemical analysis stands out as the most suitable method for ensuring and managing pool and spa water quality.