The extech cl200 waterproof total residual chlorine tester is a robust and waterproof ip67 measuring stick the high accuracy and the replaceable measuring electrode is distinguished from the compact devicethe cl200 is a revolutionary first of its kind measurement device that offers direct reading of total chlorine from 001 to 1000 ppm in addition to the numerical display of the measurement these units have a bar graph display and a measurement memory for this type of electrode method a