HL4 Multiprobes

 HL4® multiprobes

The Hydrolab HL4® is the next generation multiparameter water quality instrument from OTT Hydromet. Its reliability, ease-of-use, and metadata produce water quality data you can trust.

HL4 Features:

  • Self-monitoring system reports the status of the instrument, flags the data, and shows the user where the problem is with assistance on how to solve the issue
  • User-scheduled calibration and maintenance intervals indicate when they are due
  • Guided and semi-automated calibration routines lead the user through the calibration process
  • Calibration results are stored with date and time, calibration type, user identification, and user notes
  • Check Calibration process allows the user to verify calibration and store the results
  • Calibration reports contain information about previous calibrations and calibration checks
  • Sensor status is saved with every line of data and is contained in the log file
  • Dedicated communications modules allow easy integration with data loggers and telemetry systems
  • Compatible with the Surveyor HL – a fully IP67 handheld designed for field use with a full-color screen that is visible in direct sunlight


For measurement of popular water quality parameters in:

  • Freshwater rivers and streams, lakes and reservoirs, and groundwater wells
  • Salt or brackish water bays, estuaries, and near-coastal areas
  • Attended monitoring, continuous unattended and real-time monitoring

Available Sensors:

  • Temperature, Conductivity, pH, LDO (Luminescent Dissolved Oxygen), Depth and Turbidity


  • Diameter: 4.44 cm (1.75 in.) without rubber bumpers 
  • Length: 51.43 cm (20.25 in.) to 77.787 cm (30.625 in.) depending on configuration
  • Weight 2.2 kg (5 lb) with internal battery pack and storage/calibration cup 
  • Depth rating: 200 meters (656 ft) Deployment cable or mooring cap must be installed. Some sensors cannot be used at 200 m (656 ft). 
  • Communications: Hydrolab communications modules: USB, SDI-12, RS232, RS485, or TTY. A USB Commu- nications Module is included with a sonde. Others are sold separately. 
  • User interface: Hydrolab Operating Software on Microsoft Windows OS (Windos XP with Service Pack 3 or later)
  • Power requirements
    • -  External: 6–24 VDC (12 VDC nominal applied to the communications module. 12 VDC: 250 mW average, 19 W peak
    • -  Internal (optional): Internal alkaline D-cell battery, non-rechargeable. 
  • Loging:  4 GB of internal memory; 1 second interval minimum. Sufficient memory to keep 5 years of continuous measurements with a 15 minute logging interval.
  • Sensors: Temperature sensor plus 4 additional universal sensor ports and optional depth 
  • Operating temperature:  –5 to 50 °C (23 to 122 °F), non-freezing Operating outside this temperature range may result in mechanical damage or faulty electronic performance. 

     ( See vidoes below ) 

Hydrolab Operating Software

The Hydrolab Operating Software is the PC-based application for interfacing with Hydrolab HL Series sondes, the Hydrolab Surveyor HL, and Hydrolab communications modules.  It is designed for intuitive water quality data collection, sensor calibration, settings adjustment, and metadata access.


  • Know your instrument is working correctly with instrument and sensor statuses that are shown
  • Calibrate sensors and check sensor calibrations with guided and semi-automated calibration routines
  • Monitor water quality data real-time or set up a log file for long term monitoring
  • Access and create metadata that give system information, calibration history, user information, and site information
  • Configure sonde, sensor, and communications settings
  • Compatible with any recent version of a full Microsoft Windows Operating System on a laptop, desktop, or ruggedized device

     ( See vidoes below ) 


Compatible with Microsoft Windows XP SP3, Vista, 7 (32 bit or 64bit) or 8.  ( See vidoes below ) 

3-Minute video highlighting the new Hydrolab platform:

HL4 operating software - Overview:

HL4 operating software - Calibration: 

HL4 operating software - Monitoring and Logging: 

For a quote please email your request to sales or call 512-846-2893 

          © Hydrotech ZS Consulting 2022