What is the first step to take in treating a pool after heavy rain?

The first step to take in treating a pool after heavy rain is to test the water chemistry. Rainwater can significantly affect the pool's chemical balance, introducing contaminants and diluting existing sanitizers like chlorine. By testing the water, you can accurately assess the levels of pH, chlorine, alkalinity, and other important parameters. This information is crucial for determining the necessary adjustments needed to restore the pool to safe and sanitized conditions.

Understanding the water chemistry allows pool operators to make informed decisions about the appropriate treatments, such as adding chlorine, adjusting pH levels, or addressing any other imbalances. Without this initial testing, any subsequent actions might be ineffective or even harmful to the pool's water quality.