Water Quality Monitor (WQM)

The Water Quality Monitor (WQM) is designed to deliver core biogeochemical water quality parameters in coastal ecosystems from a single integrated package.

Accurate data, unattended

WET Labs and Sea-Bird Electronics have teamed to bring offshore research-grade measurement technology to inshore and estuarine research through ocean observing applications. The WQM incorporates WET Labs' fluorometer-turbidity and Sea-Bird's CTD sensors, providing temperature, salinity, depth, dissolved oxygen, chlorophyll fluorescence, turbidity and backscattering data.

The WQM sensors have the accuracy and precision to track subtle long-term changes in even the cleanest marine systems. By combining multiple active and passive anti-fouling features, the WQM assures this data quality in coastal and inshore regimes. Extensive field trials have demonstrated the WQM's unprecedented long-term stability in biologically rich coastal waters.

Built for extended deployment 

Typically, biofouling and sediment loads are the dominant factors that degrade and limit the data quality. These factors can overwhelm inadequately protected sensors and invalidate their data—often in just a few days. Effective long term monitoring demands the highest data quality over weeks and months. The key to cost effective data collection requires a sensor package that can withstand the environmental hazards of coastal waters. The WQM employs active flow control, passive flow prevention, light-blocking, active biocide injection and passive inhibitors to effectively and safely combat internal and external fouling. With fouling minimized, the superior inherent stability of the WQM sensors translates directly to superior long-term data quality.

Cost effective—now and later

The cost of monitoring is tied to the instrument life cycle and real value is ultimately provided through quality data, day after day, month after month, year after year. The WQM provides quality data while dramatically reducing the need for field and factory service. The bottom line: the WQM delivers unequaled long-term data quality and minimizes operational and maintenance costs.

Anti-Fouling Features

  • Pump-controlled flow
  • Extensive copper cladding
  • BLeach Injection System (BLIS) protects DO sensor and CTD flow path
  • Anti-Foulant (AF) collar for conductivity cell (EPA approved)
  • Light-blocked sample chambers
  • Bio-wiper protects optical components 


Range0-9 S/m
Accuracy0.003 mS/cm
Resolution0.00005 S/m


Range0-100 or -200 m
Accuracy 0.1% Full Scale
Resolution0.002% Full Scale


Rangec 0-50 µg/I
Accuracyd0.2% FS µg/I


0.04% FS µg/I

0.02% FS/deg C

WavelengthEX/EM 470/695 nm


ConnectorMCBH-6-MP, MCBH-4-FS
Input9-16 VDC

Sample rate

1 Hz
Current draw 

<100 mA Sampling

350 mA Peak

< 50 µA Sleep


Rangea -5-35 deg C
Accuracyb0.002 deg C
Resolution0.001 deg C


Range120% of saturation (150% upon request)
Accuracy2% of saturation
Resolution0.035% of saturation (0.003 ml/l at 0 C, 35 PSU)


Range0-25 NTU
Accuracy0.1% FS NTU

0.04% FS NTU

Wavelength700 nm


Depth200 m
Pressure housingAcetal copolymer, ABS, PVC, titanium, copper
Dimensions65.4 cm long x 18.5 cm max OD
Weight in air5.4 kg
Weight in water1.8 kg

a. Oxygen range is relative to surface saturation.

b. +/- 0.2 mg/l or 2% of reading, whichever is greater.
c. Available measurement ranges:
  • 0–30 μg Chl/l, 0–10 NTU
  • 0–50 μg Chl/l, 0–25 NTU
  • 0–50 μg Chl/l, 0–100 NTU
  • 0–75 μg Chl/l, 0–200 NTU
  • 0–125 μg Chl/l, 0–350 NTU
  • 0–250 μg Chl/l, 0–1000 NTU
d. Chlorophyll fluorescence is created by living organisms and is subject to taxonomical and physiological changes. Field calibration is highly recommended. See user’s guide for standard protocols.
e. Depth rating is the lesser of 200 m or the pressure sensor rating.
Specifications are subject to change without notice.

For all WQMX's and WQM's with v1.5X firmware.

Released June 15, 2015
WQMHostv159a.exe for Windows XP/Vista/7

For older WQM's with v1.2X firmware

Released June 16, 2011
WQMHostv126.exe for Windows XP/Vista/7
Product Datasheet

WQM datasheet

Monday, December 5, 2016
Product Datasheet

WQMx datasheet

Monday, December 5, 2016

WQMX product drawing

Tuesday, February 12, 2013
538102 - General Dimensions.PDF

WQM product drawing

Tuesday, February 12, 2013
Product Manual

WQM user manual

Thursday, April 27, 2017
Technical Note

Cable and Bulkhead Connector Maintenance

Thursday, March 9, 2017
Technical Note

Disable BLIS operation on WQM

Thursday, March 9, 2017
Disable BLIS operation on WQM.pdf
Technical Note

Instrument Voltage Ranges (in VDC)

Thursday, June 21, 2012
Technical Note

WQM Testing and Troubleshooting Commands

Friday, June 22, 2012

How do I set up my WQM for deployment?

Set up the WQM for Deployment: Please read more here.

How do I save and retrieve data from my WQM?

Managing WQM Data: Please read more here.

What should I use to lubricate bulkhead connectors?

WET Labs recommends keeping the connectors on your meter lubricated using a good quality silicone spray lubricant, such as 3M Silicone Spray or Loctite 8021 spray. These can be purchased at your local hardware store. Avoid silicone grease. It is messy and attracts contaminants. 

Do not use WD-40. It will destroy connectors.

Do you want WET Labs to review your data?

In order for data questions to be answered in an efficient manner, WET Labs requests:

-  The serial number of the instrument data in question. The most current calibration information
can be verified and the instrument settings upon delivery can be checked.

-  Description of the deployment configuration. Questions to consider:

  •   What are the current instrument settings?
  •   What is the instrument orientation?
  •   Are there possible obstructions?
  •   Is it being used in a mooring, a profiler, or being towed?
  •   What were the deployment date and geographical location?
  •   How far into the deployment was the problem seen?
  •   What power supply and cabling are being used?
  •   What was the instrument condition during the last field service or retrieval?
  •   Do you have any pictures?

-  Raw data files of the physical data in question

  •   examples of good raw data.
  •   examples of questionable raw data .

-  Information about how the raw data was processed.

What are the sensor check procedures for Water Quality Monitoring?

How do I test and troubleshoot commands?

The testing or troubleshooting functions of the WQM can only be used while the WQM is in Standby Mode. Please contact WET Labs before using the commands below. Changing any settings at this level may compromise the performance or stability of the meter. Download PDF technical note.

How do I test my meter's functionality?

WQM Bench Test: Please read more here.