What equipment is primarily used to measure pool water levels and pH?

The most reliable and effective equipment for measuring pool water levels and pH is test kits or electronic testers. These devices are specifically designed to analyze the chemical composition of pool water, providing accurate readings of pH levels, which is crucial for maintaining proper water balance and ensuring swimmer safety.

Test kits typically use reagents that change color in response to certain chemical concentrations, allowing for a visual determination of pH and other factors. Electronic testers, on the other hand, provide digital readings and can often test multiple parameters simultaneously, making them convenient for routine monitoring of pool water quality.

In contrast, the other options—swim gauges, water thermometers, and ultraviolet sensors—serve different purposes. Swim gauges are not designed for measuring chemical levels in the water. Water thermometers simply measure temperature, which does not provide information about pH or chemical balance. Ultraviolet sensors monitor UV levels in the water, important for understanding disinfection but unrelated to pH measurement or water levels. Thus, test kits or electronic testers are the correct tools for the role described in the question.