The water property will change after long time using. Want to know if the water do harm to your skin or if it"s within the safe range ( neither too acid or alkaline)? Get this this handheld water tester, you can easily test the swimming pool PH and Chlorine level and enjoy swimming with 100% satisfaction.Description:Electronically tests the PH and chlorine level of waterSuitable for swimming pool and spa water testing.This Water Tester designed for easy use and easy storageNo chemical agent requiredAccurate test and easy reading in both color and numericsPowered: 1 AA battery (not included)Dimensions: 142 x 90 x 30mmNote: safety measure range for Chlorine level is from 1.2 to 1.7 ppm and the safety measure range for PH level is from 7.2 to 7.8.