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SBE 63

SBE 63 Optical Dissolved Oxygen (DO) Sensor

High-accuracy optical sensor with 1 Hz sampling, RS-232 serial output, fully and individually calibrated. For use in CTD pumped flow path.

The SBE 63 is an individually calibrated, high-accuracy, optical oxygen sensor to assist in critical hypoxia and ocean stoichiometric oxygen chemistry research on a variety of moored and float-based platforms. Careful choices of materials and geometry are combined with superior electronics and calibration methodology to yield significant gains in performance.

The SBE 63 is designed for use in a CTD’s pumped flow path, providing optimal correlation with CTD measurements. The elapsed time between the CTD and associated oxygen measurement is easily quantified, and corrected for, in post-processing. The plumbing’s black tubing blocks light, reducing in-situ algal growth.


  • 1 Hz sampling speed, RS-232 output.
  • Each sensor fully and individually calibrated (valid for 0 - 450 µmol/kg oxygen, 0 - 30 °C, 0 - 35 psu, 0 - 2000 dbars).
  • For use in CTD pumped flow path, optimizing correlation with CTD measurements.
  • 600 or 7000 m housing.
  • Configurations:
    - With optional sensor mount for use on CTD RS-232 auxiliary sensor channel, or
    - Integrated with SBE 37 MicroCAT CTD, Sea-Bird Navis float CTD, or SBE 41 Argo float CTD.
  • Five-year limited warranty.


Each SBE 63 is calibrated individually in a temperature-controlled bath. Bath temperatures are varied at each of 4 oxygen values, providing a comprehensive 24-point calibration. Two reference sensors in each bath are standardized against Winkler titrations. Response time tests are conducted on each sensor, using gas. Salinity and pressure impacts on sensor response are each checked at two separate points.


  • Optional sensor mount interfaces to the RS-232 auxiliary sensor connector of the SBE 16plus V2, 16plus-IM V2, or 19plus V2 SeaCAT CTD. Configuration choices include SBE 63 with 600 or 7000 m housing; SBE 63 sensor mount rated to 5000 or 7000 m with XSG or wet-pluggable MCBH connector.
  • SBE 63 with a 600 or 7000 m housing is integrated into an SBE 37 MicroCAT (IMP-ODO or SMP-ODO).
  • On a Sea-Bird Navis float CTD or SBE 41 Argo float CTD, the SBE 63 with 7000 m housing is physically integrated with the CTD. Electronic operation of the SBE 63 requires an RS-232 interface in the Argo float controller.


Measurement Range 120% of surface saturation in all natural waters (fresh and salt)
Initial Accuracy larger of ±3 µmol/kg (equivalent to 0.07 ml/L or 0.1 mg/L) or ±2%
Sample-Based Drift < 1 µmol/kg/100,000 samples (20 °C)
Reesolution 0.2 µmol/kg
Response time (Tau, 63% response): < 6 sec (20 °C)
Sampling Speed 1 Hz (1 sample/sec)


Input Power 6 - 24 VDC; 35 mA (0.08 J/sample)
Output Signal RS-232, 600 - 115,200 baud (user-selectable), 8 data bits, no parity, 1 stop


SBE 63 Sensor 600 m Plastic housing: 245 g in air
7000 m Titanium housing: 270 g in air
Optional Sensor Mount for SeaCAT 5000 m Plastic mount: 190 g in air
7000 m Titanium mount: 545 g in air


SBE 63 sensor for integration with SBE 37 ODO MicroCAT, or SBE 41 CTD for Navis and other Argo floats


SBE 63 sensor installed in sensor mount for use with RS-232 auxiliary sensor channel on CTD
Note: Sensor mount rated to 5000 m (plastic) or 7000 m (titanium); dimensions are identical.



The list below includes (as applicable) the current product brochure, manual, and quick guide; software manual(s); and application notes.

For older SBE 63 product manuals, organized by instrument firmware version, click here.

Title Type Publication Date PDF File
SBE 63 Brochure Product Brochure Monday, December 29, 2014 63brochureDec14.pdf
SBE 63 Quick Guide Product Quick Guide Tuesday, March 31, 2015 63_ReferenceSheet_006.pdf
SBE 63 Manual Product Manual Wednesday, March 29, 2017 63_011.pdf
Long-Term Stability of a Moored Optical Oxygen Sensor in an Estuary Scientific Poster Monday, March 7, 2016 Jaeger_et_al_OSM_2016_Poster_SBE63 Stability.pdf
AN42: ITS-90 Temperature Scale Application Notes Wednesday, May 18, 2016 appnote42May16.pdf
AN57: Connector Care and Cable Installation Application Notes Tuesday, May 13, 2014 appnote57Jan14.pdf
AN68: Using USB Ports to Communicate with Sea-Bird Instruments Application Notes Friday, October 19, 2012 appnote68Oct12.pdf
SeatermV2© is a terminal program launcher for setup and data upload of Sea-Bird instruments developed or redesigned in 2006 and later. The common feature of this generation of instruments is the ability to output status responses in XML. SeatermV2 is part of our Seasoft V2 software suite.
Version 2.6.1 released June 1, 2016
SeatermV2.6.1-b12.exe for Windows 7/8/10

How often do I need to have my instrument and/or auxiliary sensors recalibrated? Can I recalibrate them myself?

General recommendations:

  • Profiling CTD — recalibrate once/year, but possibly less often if used only occasionally. We recommend that you return the CTD to Sea-Bird for recalibration. (In principle, it is possible for calibration to be performed elsewhere, if the calibration facility has the appropriate equipment andtraining. However, the necessary equipment is quite expensive to buy and maintain.) In between laboratory calibrations, take field salinity samples to document conductivity cell drift.
  • Moored CTD — recalibrate at least once/year, but possibly more often depending on the degree of bio-fouling in the water.
  • Thermosalinograph — recalibrate at least once/year, but possibly more often depending on the degree of bio-fouling in the water.
  • DO sensor —
    — SBE 43 — recalibrate once/year, but possibly less often if used only occasionally and stored correctly (see Application Note 64), and also depending on the amount of fouling and your ability to do some simple validations (see Application Note 64-2)
    — SBE 63 — recalibrate once/year, but possibly less often if used only occasionally and stored correctly and also depending on the amount of fouling and your ability to do some simple validations (see SBE 63 manual)
  • pH sensor —
    — SBE 18 pH sensor or SBE 27 pH/ORP sensor — recalibrate at the start of every cruise, and then at least once/month, depending on use and storage
    — Satlantic SeaFET pH sensor — recalibrate at least once/year. See FAQ tab on Satlantic's SeaFET page for details (How often does the SeaFET need to be calibrated?).
  • Transmissometer — usually do not require recalibration for several years. Recalibration at the manufacturer’s factory is the most practical method.

Profiling CTDs:

We often have requests from customers to have some way to know if the CTD is out of calibration. The general character of sensor drift in Sea-Bird conductivity, temperature, and pressure measurements is well known and predictable. However, it is very difficult to know precisely how far a CTD calibration has drifted over time unless you have access to a very sophisticated calibration lab. In our experience, an annual calibration schedule will usually maintain the CTD accuracy to within 0.01 psu in Salinity.

Conductivity drifts as a change in slope as a result of accumulated fouling that coats the inside of the conductivity cell, reducing the area of the cell and causing an under-reporting of conductivity. Fouling consists of both biological growth and accumulated oils and inorganic material (sediment). Approximately 95% of fouling occurs as the cell passes through oil and other contaminants floating on the sea surface. Most conductivity fouling is episodic, as opposed to gradual and steady drift. Most fouling events are small and mostly transitory, but they have a cumulative affect over time. A severe fouling event, such as deployment through an oil spill, could have a dramatic but only partially recoverable effect, causing an immediate jump shift toward lower salinity. As fouling becomes more severe, the fit becomes increasingly non-linear and offsets and slopes no longer produce adequate correction, and return to Sea-Bird for factory calibration is required. Frequently checking conductivity drift is likely to be the most productive data assurance measure you can take. Comparing conductivity from profile to profile (as a routine check) will allow you to detect sudden changes that may indicate a fouling event and the need for cleaning and/or re-calibration.

Temperature generally drifts slowly, at a steady rate and predictably as a simple offset at the rate of about 1-2 millidegrees per year. This is approximately equal to 1-2 parts per million in Salinity error (very small).

Pressure sensor drift is also an offset, and annual comparisons to an accurate barometer to determine offset will generally keep the sensor within specification for several years, particularly as the sensors age over time.

Do I need to clean the exterior of my instrument before shipping it to Sea-Bird for calibration?

Remove as much biological material and/or anti-foul coatings as possible before shipping. Sea-Bird cannot place an instrument with a large amount of biological material or anti-foul coating on the housing in our calibration bath; if we need to clean the exterior before calibration, we will charge you for this service.

  • To remove barnacles, plug the ends of the conductivity cell to prevent the cleaning solution from getting into the cell. Then soak the entire instrument in white vinegar for a few minutes. After scraping off the barnacles and marine growth, rinse the instrument well with fresh water.
  • To remove anti-foul paint, use a Heavy Duty Scotch-Brite pad ( or similar scrubbing device.

What are the recommended practices for connectors - mating and unmating, cleaning corrosion, and replacing?

Mating and Unmating Connectors:

It is important to prepare and mate connectors correctly, both in terms of the costs to repair them and to preserve data quality. Leaking connectors cause noisy data and even potential system shutdowns. Application Note 57: Connector Care and Cable Installation describes the proper care and installation of connectors for Sea-Bird instruments. The Application Note covers connector cleaning and cable or dummy plug installation, locking sleeve installation, and cold weather tips.

Checking for Leakage and Cleaning Corrosion on Connectors:

If there has been leakage, it will show up as green-colored corrosion product. Performing the following steps can usually reverse the effect of the leak:

  1. Thoroughly clean the connector with water, followed by alcohol.
  2. Give the connector surfaces a light coating of silicon grease.

Re-mate the connectors properly — see Application Note 57: Connector Care and Cable Installation and 9-minute video covering O-ring, connector, and cable maintenance.

Replacing Connectors:

  • The main concern when replacing a bulkhead connector is that the o-rings on the connector and end cap must be prepared and installed correctly; if they are not, the instrument will flood. See the question below for general procedure on handling o-rings.
  • Use a thread-locking compound on the connector threads to prevent the new connector from loosening, which could also lead to flooding.
  • If the cell guard must be removed to open the instrument, take extra care not to break the glass conductivity cell.

What are the recommended practices for storing sensors at low temperatures, and deploying at low temperatures or in frazil or pancake ice?


Large numbers of Sea-Bird conductivity instruments have been used in Arctic and Antarctic programs.

Special accommodation to keep temperature, conductivity, oxygen, and optical sensors at or above 0 C is advised. Often, the CTD is brought inside protective doors between casts to achieve this.

Conductivity Cell

When freezing is possible, we recommend that the conductivity sensor be stored dry. Remove larger droplets of water by blowing through the cell. Do not use compressed air, which typically contains oil vapor. Attach a length of Tygon tubing to each end of the conductivity cell to close the cell ends. See Application Note 2D: Instructions for Care and Cleaning of Conductivity Cells for details.

There are several considerations to weigh when contemplating deployments at low temperatures in general, and in frazil or pancake ice:

  • Ensure that the instrument is at or above water temperature before it is deployed. If the cell gets colder than 0 to -2 ºC while on deck, when it enters the water a layer of ice forms inside the cell as the cell warms to ocean temperature. If ice forms inside the conductivity cell, measurements will be low of correct until the ice layer melts and disappears. Thin layers of ice will not hurt the conductivity cell, but repeated ice formation on the electrodes will degrade the conductivity calibration (at levels of 0.001 to 0.020 psu) and thicker layers of ice can lead to glass fracture and permanent damage of the cell.
  • For accurate measurements, keep ice out of the sensing region of the conductivity cell. The conductivity measurement involves determining the electrical resistance of the water inside the sensor. Ice is essentially a non-conductor. To the extent that ice displaces the water, the conductivity will register (very) misleadingly low. Some type of screening is necessary to keep ice out of the cell. This is relatively easy to arrange for the Sea-Bird conductivity cell, which is an electrode-type cell, because its sensing region is totally inside a long tube; plastic mesh could be positioned at each end and would have zero effect on accuracy and stability.

The above considerations apply to all known conductivity sensor types, whether electrode or inductive types. 

If deploying at low temperatures but no surface frazil or pancake ice is present, rinse the conductivity cell in one of the following salty solutions (salty water depresses the freezing point) to prevent freezing during deployment. But this does not mean you can store the cell in one of these solutions outside . . . it will freeze.

  • Solution of 1% Triton in sterile seawater (use 0.5-micron filtered seawater or boiled seawater),   or
  • Brine solution (distilled seawater or homemade salt solution that is higher than 35 psu in salinity).

Note that there is still a risk of forming ice inside the conductivity cell if deploying through frazil or pancake ice on the surface, if the freezing point of the salt water is the same as the water temperature. Therefore, we recommend that you deploy the conductivity cell in a dry state for these deployments.

Commercially available alcohol or glycol antifreezes contain trace amounts of oils that will coat the conductivity cell and the electrodes, causing a calibration shift, and consequently result in errors in the data. Do not use alcohol or glycol in the conductivity cell.

Temperature Sensor

In general, neither the accuracy of the temperature measurement nor the survival of the temperature sensor will be affected by ice.

Oxygen Sensor

For the SBE 43 and SBE 63 Dissolved Oxygen sensor, avoid prolonged exposure to freezing temperature, including during shipment. Do not store with water (fresh or seawater), Triton solution, alcohol, or glycol in the plenum. The best precaution is to keep the sensor indoors or in some shelter out of the cold weather.

Family . Housing Compatibility
63 . 1 – 600 m (plastic) 1 – SBE 37 ODO MicroCAT
    2 – 7000 m (titanium) 2 – SeaCAT or Argo float

Example: 63.12 is an SBE 63 with 600 m housing, which is compatible with a SeaCAT or Argo float (mount and cable not included). See table below for description of each selection:

63 Optical Dissolved Oxygen Sensor - Sea-Bird optical sensor for pumped CTD applications (recommended for moored use), RS-232 temperature-compensated oxygen signal. Includes plenum and complete documentation.  
SBE 63 Housing/Dome Selections — MUST SELECT ONE
63.1x 600 meter plastic housing dome  
63.2x 7000 meter titanium housing dome  
SBE 63 Compatibility Selections — MUST SELECT ONE
63.x1 Compatible with SBE 37 ODO MicroCAT


63.x2 Compatible with SeaCATs or Argo floats (mount and cable not included)
SBE 63 Spares & Accessories
50510 SBE 63 sensor mount kit/flow chamber for SeaCATs, 5000 m depth rating, XSG connector Use for mounting SBE 63 to SBE 16plus V2, 16plus-IM V2, or 19plus V2 SeaCAT. Kit includes sensor mount, clamp, & tape.
Note: SBE 63s manufactured prior to April 2013 had a different hardware configuration, and required a different sensor mount (802096 with XSG connector, 802127 with wet-pluggable MCBH connector). If ordering a mount for an SBE 63 purchased previously, provide SBE 63 serial number so we can verify correct sensor mount. (Click here to see an example of where to find the serial number on your instrument.)
50511 SBE 63 sensor mount kit/flow chamber for SeaCATs, 5000 m depth rating, Wet-pluggable MCBH connector
50584 SBE 63 sensor mount kit/flow chamber for SeaCATs, 7000 m depth rating, XSG connector
50585 SBE 63 sensor mount kit/flow chamber for SeaCATs, 7000 m depth rating, Wet-pluggable MCBH connector
17088 SBE 63 interface cable, XSG connectors, 1.1 m (DN 30567) This interface cable is compatible with SBE 16plus V2, 16plus-IM V2, 19plus, or 19plus V2, if connecting just SBE 63 to bulkhead connector on CTD. If connecting 2 sensors to 1 bulkhead connector, a Y-cable is required in place of one of these straight cables.
171792 SBE 63 interface cable, Wet-pluggable MCIL connectors (DN 32810)
90087 Universal plumbing kit (includes pump air release valve, Y-fitting, and tubing) — Application note 64-1 Application Note 64-1 details installation of plumbing for SBE 43 & pump on CTD (details for SBE 63 are similar).
31450 Tygon tubing, 1/2" ID X 3/4" OD, 2 m, Black — main plumbing, minimizes light exposure

31450 is main plumbing, attaches to pump, conductivity sensor, 1/2" nylon hose barb Y-fitting, etc. For moored applications, it is recommended in place of 30388 plumbing tubing (shown in photo of SBE 9plus) to minimize exposure to light, improving resistance to bio-fouling. Sea-Bird uses this black tubing on all moored instruments (SBE 16plus/16plus V2 and 16plus-IM/16plus-IM V2 CTDs). Customers may field retrofit plumbing on existing systems.


Many cables, mount kits, and spare parts can be ordered online.


To SBE 16plus, 16plus-IM, 16plus V2, 16plus-IM V2, 19plus, 19plus V2

  • 17088 To CTD (RMG connectors), 1.1 m, DN 30567
  • 171792 To CTD (Wet-pluggable connectors), 1.1 m, DN 32810

Mount Kits

To SBE 16plus V2, 16plus-IM V2, or 19plus V2

  • 50510  Sensor mount kit with XSG connector (802296 sensor mount, clamp, and tape)
  • 50511  Sensor mount kit with wet-pluggable MCBH connector (802297 sensor mount, clamp, and tape)

Note: SBE 63s manufactured prior to April 2013 had a different hardware configuration, and required a different sensor mount (802096 with XSG connector, 802127 with wet-pluggable MCBH connector). If ordering a mount for an SBE 63 purchased previously, provide SBE 63 serial number so we can verify correct sensor mount. (Click here to see an example of where to find the serial number on your instrument.)

Compare Oxygen Sensors

SBE Sensor Type Output Depth (m) User-
Can be
Integrated with
SBE 43 Dissolved Oxygen Sensor membrane 0 - 5 volts 600, 7000   Moored CTDs
(with 1.0-mil membrane),
Profiling CTDs
(with 0.5-mil membrane)
SBE 43F Dissolved Oxygen Sensor membrane frequency 600, 7000   Moored CTDs
(with 1.0-mil membrane),
profiling CTDs
(with 0.5-mil membrane)
SBE 63 Optical Dissolved Oxygen (DO) Sensor optical RS-232 600, 2000, 7000 Moored CTDs or slow profiling CTDs
** Products are no longer in production. Follow the links above to the product page to retrieve manuals and application notes for these older products.