A pH meter, also called a sensor or tester, is a device used to measure the acidity or alkalinity of a substance. A pH meter has either a portable or a benchtop body. Many portable meters are handheld devices. Some testers have an internal sensor and may have a tip and body that fit inside of a container for measurement. A meter is commonly used in many different environments from laboratories to field research and manufacturing facilities. Researchers, manufacturers, and hobbyists use a pH meter in aquaculture, agriculture, wine-making, and water-testing, and for scientific applications. An EC meter measures the electrical conductivity in a solution. It is commonly used in hydroponics, aquaculture and freshwater systems to monitor the amount of nutrients, salts or impurities in the water.