A pH tester, also called a pH sensor or pH meter, is a device used to measure the acidity or alkalinity of a substance. pH can be tested using paper strips or a pH tester. Digital pH testers are more accurate than pH test strips, which are often used to obtain approximate readings or in education. pH testers are available as benchtop models, which are designed for use in laboratories, or as portable models, which are designed for laboratory and field use. Testers usually require periodic calibration using a buffer standard. Researchers, manufacturers, and hobbyists use pH testers for applications including aquaculture, soil testing, wine making, water testing, and to ensure food safety in food and beverage production.
Some meters test multiple types of samples while others are designed for testing a specific type of specimen or within a specific pH range. Because soil pH is an important factor in plant health and crop production, soil pH testers are often used in agriculture and by home gardeners to ensure that the soil pH meets the requirements of the specific crops they are growing. A soil pH tester usually has a probe made of steel to protect it from damage by rocks and other impediments. Researchers and health and environmental specialists use water pH testers to ensure the safety of drinking water and the health of freshwater and saltwater bodies, including creeks, rivers, lakes, and oceans. Handheld or portable water pH testers usually float and often meet Ingress Protection (IP) standards for protection against water penetration. Testers used to test solids or slurries often have an anti-clogging probe.
When selecting a pH tester for purchase, consider the intended application, which pH range will be measured, readability, the required degree of accuracy, probe type, which parameters are required, and temperature compensation. Because some pH testers also measure additional parameters, it's important to know which parameters your application requires. These may include dissolved oxygen (DO), conductivity (also called electro-conductivity or EC), temperature, total dissolved solids (TDS), salinity, resistivity, or oxygen reduction potential (ORP)/mV. Meters that measure four or more parameters are called multiparameter meters.