A pH Meter / pH Tester is used in laboratories, industrial plants, aquariums, swimming pools and more to measure the pH value. For example, in industrial sewage treatment plants, different types of wastewater (coming from household sewage and biological and chemical processes) cause various and rapid changing pH measurement data. Continuously working pH controllers primarily are used to regulate the wastewater treatment process. However, for taking quick measurements and to adjust and check these fixed-installation pH controllers and pH indicators, a handheld pH Meter / pH Tester is especially handy.