Hach 9532700 Pocket Pro+ Multi 1 Water Quality Tester - Measures Conductivity, TDS & Salinity with Replaceable Sensor | Ideal for Aquariums, Pools & Industrial Water Testing

Works great and so easy to use. Our pool store uses the same one and showed me how to use it. If there is a down side, the instructions are inadequate, so thanks for my pool store who said the same about the enclosed instructions. It still gets five stars, because it is about the product and not the user manual.