This compact pen-style 3-in-1 water quality tester measures TDS, electrical conductivity and liquid temperature simultaneously, eliminating the need for separate testing devices to simplify daily water monitoring. Built with high-sensitivity titanium alloy probe and built-in ATC automatic temperature compensation, it delivers steady ±2% accurate readings within 0–9990ppm TDS and 0–9990µS/cm EC ranges, effectively offsetting data errors caused by fluctuating water temperature. Equipped with a clear digital LCD screen, it supports practical data hold, unit switch and auto power-off functions to extend battery service life. Made of lightweight splash-proof ABS plastic with a matched protective probe cap, its ergonomic portable design fits pockets for on-site sampling. Pre-calibrated at factory for instant use, it features one-button quick recalibration for long-term stable detection. Widely suitable for drinking water purity check, hydroponic nutrient adjustment, aquarium tank maintenance, swimming pool care, lab reagent preparation and small-scale wastewater testing, this cost-effective meter serves home users, hydroponic growers and aquarists perfectly.