HI981409 and HI981410 TDS and EC meters have been specifically designed to address the needs of operators in hydroponics, greenhouses and nurseries HI981409 TDS Tester for Fertigation Solution Lightweight and it floats! Water resistant Ideal for mixing fertilizer Automatic calibration Automatic Temperature Compensation HI 981409 TDS tester has been specifically designed to address the needs of operators in hydroponics, greenhouses and nurseries. Calibration is easy and completely automatic. Simply press and hold the on/off button for a few seconds and the meter will request the appropriate calibration solution. Place the probe in the solution and wait until it is calibrated. No extra buttons to push or dials to turn! HI 1220 probe measures 24 cm (9.4") and can be used to mix the fertilizer solution. The meter switches off after five minutes of inactivity to save battery life. The outer casing also incorporates a molded eye so that the meter can be hung right where it is needed. Specifications: Range 0 to 1999 mg/L (ppm) Resolution 1 mg/L Accuracy ±2% F.S. Calibration automatic, at 1500 ppm Temperature Compensation automatic, 5 to 50°C (41 to 122°F) with ß=2%/°C Probe HI 1220 replaceable EC/TDS probe, 240 mm (9.4") long, with DIN connector (included) Battery Type / Life 2 x 1.5V AA / approx. 3000 hours of continuous use; auto-off after 5 minutes of non-use Environment 0 to 50°C (32 to 122°F); RH max 95% Dimensions 86 x 94 x 33 mm (3.4 x 3.7 x 1.3") - meter only Weight 150 g (5.3 oz) - meter only Hanna HI981409 TDS Meter à¤Ã×èͧÇÑ´ TDS à¤Ã×èͧÇÑ´·Õ´ÕàÍÊ