The Milwaukee T75 is a handy TDS (Total Dissolved Solids) tester that indicates the level of contamination in water. The TDS Tester is designed for aquariums, aquaculture, education, water treatment and many other applications. With the Milwaukee T75 you can ensure that your fish have the correct TDS balance to keep them healthy. The TDS value also helps to monitor the effectiveness of the filter.Milwaukee waterproof TDS Tester T75+ measures Total Disolved (TDS) direct and with automatic temperature compensation+ easy-to-read, large LCD display+ ideal range for aquariums (0 to 1999 ppm)+ resolution: 1 ppm (mg/L)+ accuracy: +/- 2%+ automatic temperature compensation: 0 to 50C+ units in ppm easily convertable to uS/cm+ factory calibrated with the ability to recalibrate if needed+ 250 hours continuous use+ simple one point calibration+ fully waterproof to IP65+ replaceable TDS electrode+ batteries and calibrations solution (1382 ppm) included