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ECO BB9 Backscattering Sensor

The ECO BB9 is a sensor system for measuring optical backscattering at nine wavelengths.

Sea-Bird Scientific’s popular Environmental Characterization Optics ( ECO ) series tools determine bio-optical and physical parameters withi n natural waters. These instruments are designed as a modular suite of sens ors with special features for specific application support. The ECO series incorporates a common set of options with a single basic design to make the sensors idea for a wide variety of deployments.

The ECO BB9 is a flexible sensor system for measuring optical backscattering at nine wavelengths. The BB9 was developed to compliment the Sea-Bird Scientific family of spectral attenuation and absorption meters: the ac-9 and the new ac-s. Based on the successful line of ECO BB sensors, the BB9 uses a centroid angle of 117 degrees, which minimizes the error in extrapolating to the total backscattering coefficient

As part of an IOP package, the combination of a BB9, an ac-s and an ac-9 equipped with a 0.2 μm filter can define a, b and c: the inherent optical properties of the water column. The BB9 is designed as a flexible system. The BB9 c an be customized with any of the ECO line of optical configurations. For example, sc attering can be measured at seven wavelengths as well as CDOM and chlorophyll fluores cence. See the Triplet specifications sheet for details on the available o ptions. Further customization of the instrument is possible with pr essure and temperature sensors to provide a stand-alone profiling tool.



14.6 cm
Length 30.5 cm
Weight in air 3.1 kg
Weight in water 1.8 kg



Wavelengths (nm)
and sensitivity
Sensitivity, 488 2.14 x 10-5
Range ~ 0.0024 - 5 m-1
Linearity 99% R2



Digital output resolution 12 bit
RS-232 output 19200 baud
Connector MCBH6MP
Input 7-15 VDC
Current, typical 300 mA @ 12 volts
Sample rate 1 Hz



Temperature range 0-30 deg C
Depth rating 600 m (standard)




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

ECOView host software provides a graphical user interface that allows you to configure, collect, view, and upload data from a variety of ECO fluorometers.

Version 1.23 released April 9, 2013
File ECOView123.exe for Windows 7/8/10

How do I protect my ECO from bio-fouling?

ECO instruments are designed for long term deployment capabilities with low power requirements, a large memory and an available Bio-wiper™. The Bio-wiper™ on the ECO was designed to protect the optical surface and has been very effective under most conditions.

If extra protection is required to prevent marine organisms from attaching to the instrument body near the optical head and interfering with the operation of the Bio-wiper™ we suggest using copper foil tape. The GoMOOS project developed a technique for their ECO sensors and WET Labs recommends this technique:

Apply electrical tape under the area where copper tape will be applied. This protects the meter from the significant adhesive residue of the copper foil tape.

Apply the copper tape to the prepped surfaces. There are different width copper foil tape options, with non-conductive adhesive, available from McMaster-Carr. NOTE: when applying the coper tape, the adhesive should not be touched. This will cause the tape to not stick to the electrical tape on the meter. When submerged in salt water, the copper will adhere more closely to the meter.

As long as the electrical tape is used, this technique does not violate the ECO warranty and WET Labs will service instruments that have had copper tape applied to them.

Important! Do NOT apply copper tape directly to the meter. Its adhesive is extremely difficult to remove. Meters returned to WET Labs wrapped in copper tape without the electrical tape preparation will have additional service charges applied.


What is the fluorescent stick that came with my meter used for?

Checking Meter Output with the Fluorescent Stick
ECO meters ship with a stick of fluorescent material with which you can check your meter's output response.
    •    With the meter on and outputting data, hold the stick approximately 1/2-in (1 cm) from the lit detectors. Be careful to NOT touch the sensor face, as it scratches easily.
    •    Pivot the stick to parallel with the meter's optics; the output in the  meter's "signal" column should increase to near maximum output as given on the meter's characterization or calibration sheet.
    •    As you move the stick away, the output will decrease.


What is the memory capability?

    •    Not included on the "RT" units!!
    •    The memory is stored in "Flash" memory, an integrated circuit chip on the electronic board set.
    •    There is no removable card, no upgrade in memory capacity.
    •    The total sample records available for a single channel ECO = 108,000.
    •    Typically, the ECO output is set to 1 sample/sec.

What type of batteries are in ECO's?

    •    We recommend the use of Lithium batteries in all of our ECO battery units.
    •    There is a very significant battery life increase in comparison with Alkaline cells.
    •    We use Ultralife Lithium +9V batteries.
    •    Ultralife has 3 different part numbers (used with different sales packaging) for the long-life batteries we use in our ECO's:
    ◦    U9VL
    ◦    U9VLX
    ◦    U9VLBP
    •    Ultralife batteries have Aluminum/Mylar housing providing:
    ◦    Protection against humidity and heat from entering the battery. Humidity and heat reduce efficiency and shelf-life.
    ◦    Batteries that are much more leak-resistant.
    •    Ultralife batteries have a 7-10 year shelf-life.
    •    The batteries are customer replaceable with easy access to the battery pack.
    •    The battery pack has 6 batteries: 2 layers of 3 +9V Lithium cells.


How do I get started using my new ECO?

How do I change the ASV resolution?

How do I change the ASV resolution?

See the following Technical Note: Getting the Highest Resolution on your ECO_v1 [PDF]

What is the back scattering angle of my ECO instrument?

WET Labs ECO Centroid Angles for Back Scatter Measurements

The WET Labs’ ECO sensors have multiple back scattering angles depending upon type of sensor. This document will describe these angles based upon the type of ECO sensor selected by the customer.

Single Channel Sensors:
Single channel ECO back scatter sensors have an in-water centroid angle of 124°.  These include the following ECO models: bb, NTU.

Dual Channel Sensors:
Dual channel ECO back scatter sensors (back scatter at 700nm paired with chlorophyll fluorescence) have an in-water centroid angle of 142°. These include the following ECO models: FLNTU and FLBB versions along with OEM variants of these sensors (AP2, 2K, SLC, RTD, SB variants).

Three Channel Sensors:
Three channel ECO back scatter sensors (individually paired LED source with detector) have an in-water centroid angle of 124°. These include the following ECO models: bb3, BBFL2, BB2FL and Triplet-w family.

Combined Three Channel Sensors:
WET Labs’ combined three channel ECO back scatter sensors (back scatter at 700nm paired with chlorophyll fluorescence along with either another back scatter or FDOM channel) have an in-water centroid angle of 124°.

These include the following ECO models:
FLBB-CD, FLBB-BB along with OEM variants of these sensors (2K, AP2, SLC, REM, BOSS, 6K). MCOMS and SeaOWL UV-A: WET Labs’ MCOMS and SeaOWL UV-A back scatter sensors (back scatter at 700nm paired with chlorophyll fluorescence along with either another back scatter or FDOM channel) have an in-water centroid angle of 150°.

What is the input voltage range for my instrument?

Deriving the vertical diffuse attenuation coefficient (Kd) from the absorption coefficient (a).

Derivation of Kd from a
In what follows we have left off the dependence on wavelength. In addition we have left off effects due to inelastic scattering.
Modeling Kd(z) requires the inclusion of the depth dependence of the shape of the radiance
distribution. This can be accomplished by using Gershun's equation:
K(z) = a(z) / μ − (z)
where a(z) is the absorption coefficient and μ(z) is the average cosine of the light field.
Kd(z) differs from K(z) by only a few percent, so that we may set:
Kd(z) ≈ a(z) / μ − (z) .
Berwald et al. (1995) have derived a parametric model for the dependence of ⎯μ(z) on ωo for a vertical sun in a black sky. We will assume the same depth dependence for an ordinary sky. This is not precise, but the average cosine varies slowly and has a typical range of only about 10%. The model is:
ωo= b / c, where b and c are the total scattering and attenuation coefficients, including water.
τ = cz, is the optical depth.
μ∞(τ) = μ∞ + (μ(0) - μ∞ ) exp(-Ptt ).
μ∞ = - 1.59 ωo4 + 1.71 ωo3 - 0.467 ωo2 - 0.347 ωo + 1
μ(0)= cosine of refracted solar zenith angle
Pτ(ωo) = - 0.166 ωo2 + 0.341 ωo + 0.0305
Berwald et. al. Limnology and Oceanography 1995, vol. 40, no8, pp. 1347-1357 .