A turbidity probe works by sending a light beam into the water to be tested. This light will then be scattered by any suspended particles. A light detector is placed at (usually) a 90 degree angle to the light source, and detects the amount of light that is reflected back at it.

pH meters are simple to use and are not affected by human error such as color blindness. Some people may perceive color differently from others, or the true result. As pH meters use a readable digital display, they provide a much more precise result than pH papers and titration methods.