Oakton Waterproof pHTestr 10 is a great product to use in hydroponic applications. This pH tester is micro-processer based and features Automatic Temperature Compensation (ATC), push button three-point calibration, hold function and auto buffer recognition. You will now be able to easily and accurately read the pH of any solution. Reads a pH range of 1.0 to 15.0. Certifiable to IP67 standards.