pH is a is a scale used to measure of how acidic/basic an aquatic solution is. The scale ranges from 0 to 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. The pH of water is a very important measurement in determining the water quality. The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution.