... & coffee, pools & spa Wholesale Professional Water-proof Digital ater test instrument tds meter Description: TDS-139 TDS TestersMeasuring range:0 ... medical products, Aquatic cultivation, Boiler water, Households and offices, Aquarium water, Teaching of physics and chemistry, Electroplating water, Cooling towers ... (1382ppm 25°C) Wholesale Professional Water-proof Digital ater test instrument tds meter