Metadata Article

Learn about the importance of Metadata in water quality monitoring programs

Hydrolab HL4

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.

Hydrolab 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, Turbidity


Hydrolab HL4 Product Sheet

Hydrolab HL4 Sonde Manual

Hydrolab HL4 Sensor Manual

Hydrolab HL4 Communications Module Manual

More information on the Hydrolab HL4 and available sensors can be found at

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