Your water’s pH is a measure of how acidic or basic the water is. pH stands for “potential of hydrogen,” and the number (from 0 to 14) is determined by the concentration of hydrogen ions. A pH level lower than seven is acidic, and can contribute to corrosion. A result higher than seven is basic, and can lead to build-up of minerals around the edge of the water. Keep in mind also that the kind of water (hard vs. soft) you have and the sanitizer you use can affect your pH levels. Water alkalinity is a measure of your water’s ability to neutralize acids. High alkalinity can cause your pH levels to rise and reduce the effects of your sanitizer. Low alkalinity affects the ability of pH to regulate itself, resulting in fluctuations and possibly damage to hot tub surfaces.