pH dataloggers for remote water quality monitoring.


  • Intelligent energy management for longer battery lifetime
  • Up to 600,000 data records
  • USB connection for fast data transfer to PC
  • Replaceable pH electrode
  • User-friendly software interface

pH Dataloggers Product Description

Monitoring of water resources has become a global challenge with high priority. Therefore innovative measuring technology is essential to meet the challenge. The WQL-pH, pH dataloggers are the first launched product of the new WTW product family. The pH dataloggers meet the requirements of continuous long-term pH measurement and data logging. Applications for the WQL-pH, pH Dataloggers are characterized by the need for a large quantity of reliable data measurements at multiple measuring positions which are difficult to access. With a diameter of only 1 inch (25 mm) the pH dataloggers are ideal for both ground and surface water monitoring projects. The pH dataloggers consist of four parts including the end cap which covers the USB data transfer port, the main body which houses the battery, the replaceable long life pH electrode, and the guard that protects the pH electrode.

The pH datalogger’s huge memory can record up to 600,000 data sets containing the pH measurement, temperature, date, and datalogger ID number. This massive amount of data storage is ideal for detailed pH monitoring studies. The data is recovered from the pH dataloggers using a mini USB connection for fast data transfer directly to a PC. The pH dataloggers have a status LED which provides information on memory and measurement operation. A quick start button located under the pH datalogger’s end cap allows you to have further control over the pH measurements.

pH Datalogger’s USB port, indicator light, and quick start button.

pH Datalogger Software
A user-friendly software interface allows you easy and fast access to all important functions and settings on the pH datalogger.  The software allows you to easily follow the pH datalogger’s detailed one or two point calibration protocol and configure several key parameters including time interval, starting and stopping point, and the datalogger’s ID.  The pH datalogger software includes a graphing function to simplify data analysis.  The pH datalogger’s software can pre-filter the data by date and time then easily export the data via .CSV format to other software programs for more detailed analysis.

Power for the pH Datalogger
The pH datalogger uses a high quality lithium battery as its power source.  The pH datalogger uses special intelligent battery power management to maximize the battery life.  While the battery life is dependent upon the frequency of measurement, the battery can last up to 16 months with a sample rate of 10 minutes or more.  Changing the battery is as easy as opening the conveniently located battery compartment on the pH datalogger’s main body.

pH Datalogger Electrodes
The pH dataloggers use the SensoLyt pH electrode or ORP electrode, both with integrated temperature sensor and extremely stable polymer reference electrolyte allowing for precise measurement over a long period of time.  The pH datalogger and electrodes have a robust design with an IP 68 rating which can withstand depths up to 328 ft (100m).  The pH datalogger’s electrodes are replaceable and has a SMEK plug for easy removal and installation.  The stainless steel basket guard provides complete protection to the pH datalogger’s electrodes.

pH Datalogger’s battery compartment.

pH Datalogger Applications

The pH datalogger has many applications including:

  • Watersheds and wells
  • Dredging, mining, and boreholes
  • Rivers and lakes
  • Landfill runoff
  • Construction and restoration projects
  • Pump stations
  • Applied limnology
  • Pipes or other small diameter measuring points

pH Dataloggers Specifications

WQL-pH pH Datalogger
pH Range *: 0.000 to 20.000
mV Range *: -1000.0 to +1000.0
Temperature Range *: 23 to 221°F (-5.0 to +105.0°C)
pH Resolution: 0.001
mV Resolution: 0.1 mV
Temperature Resolution: 0.1°F (0.1°C)
pH Accuracy *: <0.005 +1 Digit
mV Accuracy *: <0.2mV +1 Digit
Temperature Accuracy *: <0.1°F (0.1°C) +1 Digit
Temperature sensor: Automatic recognition of the temperature sensor of the electrode: NTC 30 (30 k? at 25 °C / 77 °F) or Pt1000
Temperature Compensation: Automatic
Calibration: Automatic buffer detection
Measuring Medium:
Temp Range: 32 to 140 °F (0 to 60 °C)
pH Range: 2 to 12
Data Volume: up to 600,000 data records
Sampling Interval: adjustable: 1,5,10,30 s/ 1,5,10,15,30 min/ 1,2,3,6,9,12,24 hr
Power Supply: Lithium ion battery (3.6V, AA size, 2600 mAh)
Battery Life: Up to 16 months depending on the sample rate
USB Interface: Type USB 1.1, USB-B (Device), data output
Protection Rating: IP 68
Maximum Pressure/Depth: 145 PSI (10 bar)/328 ft (100 m)
Storage Temperature: -13 to 149°F (-25 to +65°C)
Material: Metal parts (Stainless steel 1.4571**), Battery Compartment (Brass, gold-plated)
Size of Probe: 0.98 inch Diameter x 15.83 inch L (25 mm dia. x 402 mm long), retaining hole 0.26 inch (6.5mm)
Weight: 1.9 lb. (860 g) including electrode
Certificates: CE

* The measuring ranges and accuracy exclusively refer to the measuring electronics of the pH datalogger without the electrode.  For the measuring ranges and accuracy of the operable pH datalogger, the specifications of the electrode and buffer solutions have also to be taken into account.
** Stainless steel can be susceptible to corrosion at chloride concentrations of >500 mg/l.

pH SensoLyt Electrode
pH Range: 2.000 to 12.000
Referenece Electrolyte: Polymer, AgCl free
Junction: Single hole junction
Shunt Element: Ag/AgCl
NTC: Yes
Temp Range: 32 to 140°F (0 to 60°C)
Membrane Resistance at 25°C: <500 MOhm
Maximum Pressure/Depth: 145 PSI (10 bar)/328 ft (100 m)
Connection: SMEK head, 6-pole
Material: Shaft: Glass, O-rings: FPM (Viton), SMEK plug: PEEK with gold plated contacts
Dimensions: 4.7 inch L x 1/2 inch Dia (120 mm L x 12 mm Dia)
Weight: 1.6 oz (45 g)

ORP SensoLyt Electrode
ORP Range: -2000.0 to 2000.0
ORP Accuracy: + 0.2
Referenece Electrolyte: Polymer
NTC: Yes
Temp Range: 32 to 140°F (0 to 60°C)
Membrane Resistance at 25°C: <500 MOhm
Maximum Pressure/Depth: 145 PSI (10 bar)/328 ft (100 m)
Connection: SMEK head, 6-pole
Material: Shaft: Glass, O-rings: FPM (Viton), SMEK plug: PEEK with gold plated contacts
Dimensions: 4.7 inch L x 1/2 inch Dia (120 mm L x 12 mm Dia)
Weight: 1.6 oz (45 g)


pH Datalogger pH Electrode (PN# 103709)
pH electrodes should be replaced every six months and calibration should be done after every replacement.

pH Datalogger ORP Electrode (PN# 103714)
ORP electrodes should be replaced every six months and calibration should be done after every replacement. NOTE: Available May 2011

pH Datalogger Battery (PN# 109825)


pH 4.01 Buffer, 250 ml bottle (PN# 108800)

pH 7.00 Buffer, 250 ml bottle (PN# 108802)

pH 10.00 Buffer, 250 ml bottle (PN# 108804)

Calibration and maintenance set (PN# 108820)
Includes 3 bottles with 250 ml each pH 4.01/ 7.00/ 10.00, 1 bottle with 250 ml pepsin cleaning solution, 1 bottle with 250 ml KCl solution 3 mol/l.


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