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Portable pH/EC/TDS/Temperature Meter with CAL Check™


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The HI9813-6 is an easy-to-use, water resistant, portable meter that measures pH, conductivity (EC), total dissolved solids (TDS), and temperature with a single probe.

The HI9813-6 features the Hanna Instruments CAL Check that will allow the user to know when the probe needs to be calibrated or replaced. The meter operation is simplified with dedicated buttons for measurement modes to be displayed on the LCD and knobs for single point calibration of pH and EC. A variable TDS conversion factor ensures that your results are right the first time.

  • 3 in 1 probe with pH, EC, TDS & temperature sensors.
  • CAL Check™ ensures the accuracy of the meter.
  • Great for hydroponics, aquariums, pools, & ponds.


The HI9813-6 portable meter features a large LCD which 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 HI9813-6 is from 0.00 to 4.00 mS/cm and TDS is from 0 to 1999 ppm. The temperature correction coefficient (β) is fixed at 2 %/oC and allows for automatic temperature compensated measurements of EC and TDS. The HI9813-6 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 battery life indicator as well as on-screen tutorial messages. The supplied HI1285-6 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 HI9813-6 is a versatile meter for the agriculture, greenhouse and hydroponics industries.

The HI9813-6 combined pH and conductivity meter also offers the CAL Check feature that alerts the user to a problem with a pH electrode. This feature is important for customers that calibrate only to pH 7.0; if there is a fracture on the pH glass of the electrode, the pH meter will always display pH 7.0 regardless of the solution being measured. This can be disastrous for the person that calibrates at pH 7.0 and takes readings of samples with an expected pH of 7.0. The user will never be aware that there is a problem with the electrode. This can result in inaccurate pH measurements, which for a greenhouse can affect the growth of the plants. Placing the HI1285-6 pH/EC electrode in the HI50021 CAL Check solution helps users determine if the probe needs to be calibrated, cleaned or replaced. When the probe is placed in solution the user presses the “Check” key. The pH TDS meter runs CAL Check diagnostics and will display either “Probe is OK” or “Clean Probe and Calibrate”. If the reading is around pH 4.0 when the probe is placed in the solution then the probe is broken and needs to be replaced.


hi1285-6 electrode

HI1285-6 polypropylene body amplified pH electrode with built-in EC/TDS and temperature sensors

The HI9813-6 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 amount 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 a 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

Water Resistant

CAL Check

Variable 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

Automatic Temperature Compensation

  • All readings are compensated for variations in temperature

Low Battery Indicator


pH Range 0.0 to 14.0 pH
pH Resolution 0.1 pH
pH Accuracy ±0.1 pH
pH Calibration manual, one point
Conductivity Range 0.00 to 4.00 mS/cm
Conductivity Resolution 0.01 mS/cm
Conductivity Accuracy ±2% F.S.
TDS Range 0 to 1999 ppm (mg/L)
TDS Resolution 1 ppm (mg/L)
TDS Accuracy ±2% F.S.
Temperature Range 0.0 to 60.0°C / 32.0 to 140.0°F
Temperature Resolution 0.1°C
Temperature Accuracy ±0.5°C /±1°F
Temperature Compensation automatic from 0 to 50°C (32 to 122°F) with β=2%/°C typical
EC/TDS Calibration manual one-point
TDS Conversion Factor Variable based on reading from 0.56 to 0.72 according to the TDS 442 curve for natural water
Electrode/Probe HI1285-5 polypropylene body, pre-amplified multiparameter probe with internal temperature sensor, DIN connector and 1m cable
Battery Type/Life 9V / approximately 150 hours of continuous use
Environment 0 to 50°C (32 to 122°F); RH max 100%
Dimensions 145 x 80 x 36 mm (5.7 x 3.1 x 1.4”)
Weight 230 g (8.1 oz)
Ordering Information HI9813-6 is supplied with HI1285-6 pH/EC/TDS/°C probe with Cal-CheckTM, HI70007 pH 7.01 buffer solution sachet (1), HI70442 1500 ppm calibration solution sachet (1), HI70031 1413 µS/cm calibration solution sachet (1), HI700661 electrode cleaning solution sachets (2), HI50021 calibration check solution sachets (2), 9V battery, instructions and rugged carrying case.
Warranty 2 years (probe 6 months)