pH/EC/TDS/Temperature Portable Meter, range: pH 0.0 to 14.0 pH EC 0.00 to 4.00 mS/cm TDS 0 to 1999 ppm (mg/L)

SKU : 81977801ad46

The HI9813-51 is a portable, water resistant meter that is designed for measuring pH, EC/TDS, and temperature when paired with its respective probe (i.e., HI1285-51).

The meters are easy to use, with dedicated keys for measurement modes that are clearly displayed on the LCD, and knobs for 1-point calibration of pH and EC. On-screen tutorial messages guide the user through calibration and measurement.

Main Features

  • 3-in-1 combination probe with pH, EC/TDS, and temperature sensors
  • Best for hydroponics, greenhouses, farming, and ground water app.
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The HI9813-51 portable meter features a large LCD that displays either pH, EC, TDS or temperature readings along with tutorial instructions. The pH readings are displayed with a 0.1 resolution and an accuracy of +/-0.1 pH while the EC and TDS readings are displayed with a 0.01 mS/cm and 1 ppm (mg/L) resolution and 2% full-scale accuracy. The EC range of the HI9813-51 is from 0.00 to 4.00 mS/cm and TDS is from 0 to 1999 ppm. The temperature correction coefficient (?) is fixed at 2 %/oC and allows for automatic temperature compensated measurements of EC and TDS. The HI9813-5 is a basic pH/EC/TDS meter that is calibrated manually to a single point with the use of two trimmers. pH is calibrated to pH 7.01 while EC/TDS is calibrated to either 1.41 mS/cm (1413 µS/cm) or 1500 ppm. The LCD screen has a battery life indicator as well as on-screen tutorial messages. The supplied HI1285-51 probe is a polypropylene body, amplified pH electrode with a built-in EC/TDS and temperature sensors. The amplifier for the pH electrode prevents interference from humidity and electrical noise from common sources including from motors, ballasts or pumps. The HI9813-51 is a versatile meter for the agricultural, greenhouse and hydroponic uses.



HI1285-51 polypropylene body amplified pH electrode with built-in EC/TDS and temperature sensors

The HI9813-51 is supplied with a polypropylene body pH/EC/TDS/temperature probe. The pH, EC, TDS, and temperature sensor are housed in a single body that connects to the meter with a DIN connector.

Amplified pH electrode

The pH electrode circuit has a built-in amplifier that will reduce the effects of electrical noise on the high impedance-pH measurement. Examples of sources of electrical noise include motors, ballasts, and pumps which are common in greenhouses.

Amperometric EC/TDS sensor

The EC/TDS readings are performed by an amperometric sensor. An alternating voltage is applied to the sensor and the amount of current that passes between the two stainless steel pins is dependent upon the number of salts (fertilizer) present. A greater amount of salt present results in an increase in conductance.

Polypropylene body

The polypropylene body houses all the sensors in single body design and is durable. The probe is gel filled for maintenance-free operation. It does not have to be refilled periodically.

  • 3 sensors in a single probe
  • Pre-amplified pH electrode for resistance to electrical noise
  • Gel filled maintenance free pH electrode

Features at-a-glance


Automatic Temperature Compensation

  • All readings are compensated for variations in temperature

EC to TDS conversion factor

  • Factor automatically adjusts from 0.56 to 0.78 based on actual EC readings
  • Factor based on 442 curve for natural water

Low Battery Indicator




Specification NameDetail
pH Range 0.0 to 14.0 pH
pH Resolution0.1 pH
pH Accuracy (@25°C/77°F)±0.1 pH
pH CalibrationManual, 1-point
Temperature Range0.0 to 70.0°C
Temperature Resolution0.1°C
Temperature Accuracy (@25°C/77°F)±0.5°C
Temperature CalibrationAutomatic from 0 to 70°C with ß=2% / °C
EC Range0 to 4000 µS/cm
EC Resolution 0.01 mS/cm
EC Accuracy (@25°C/77°F)±2% F.S.
EC Calibration Manual, 1-point
TDS Range0 to 1999 ppm (mg/L)
TDS Resolution 1 ppm
TDS Accuracy (@25°C/77°F) ±2% F.S. ppm
TDS Conversion FactorVariable, automatically adjusted from 0.56to 0.78 based on actual EC readings (based on 442 curve for natural water)
TDS CalibrationManual, 1-point
Power Supply1 x 9V Alkaline / approximately 150 hours of continuous use
Environment0 to 50°C (32 to 122 °F); 100% RH
Dimensions145 x 80 x 36 mm (5.7 x 3.1 x 1.4 “)
Weight230 g (8.1 oz.)
Warranty2 years
Recommended ProbeHI1285-51 combination, amplified pH /EC/TDS/temperature probe with built-in temperature sensor, 8-pin DIN connector and 1 m (3.3’) cable