While there's no need to go too deep into the science of it, checking and maintaining the healthy and safe pH levels under your control is vital for any swimming pool owner. Moreover, pool water must be tested on a regular basis just to make sure that it really is clean and healthy. The pH scale is a measurement of acidity or alkalinity that runs from 0 to 14. A reading between 7.2 and 7.8 is ideal; this range is safe for swimmers and helps sanitizers work at top efficiency.