Sequoia Scientific


Deep Submersible Particle Size Analyzer

The LISST-Deep instrument is a 4,000 m rated version of Sequoia’s LISST-200X workhorse.

The LISST-Deep generally has the same capabilities as the LISST-200X but extends the operating depth range to 4,000 m.




  • 4,000 meter depth rating (prior to 2020, rating was 3,000)
  • Small angle forward scattering laser diffraction technology
  • Measures particle size, concentration, beam attenuation, VSF, depth, temperature
  • Self contained with internal programmable datalogger for autonomous data collection
  • Externally powered
  • Optional external battery pack, rated to 4,000 m depth
  • USB connection to PC for programming, offloading and real-time size distribution displays
  • Integrated depth and temperature sensor
  • Power and integrate up to three external analog sensors
  • 36 size classes
  • Analog output of mean particle size and total volume concentration for CTD integration
  • Real-time output of complete Particle Size Distribution



Parameters measured

  • Particle size distribution from 1 µm to 500 µm
  • Depth (4,000 m max depth @ 0.1 m (10 cm) resolution)
  • Optical transmission @ 0.1 % resolution
  • Volume concentration @ 0.1 µl/l resolution
  • Volume scattering function (VSF)

Operating concentration range

  • Optical transmission from 0.3 to 0.985 (30 % to 98.5%)
  • Concentration range 1 mg/l to 800 mg/l (very strongly grain-size dependent)


  • Small-angle forward scattering
  • 32-ring custom photodiode ring detector for small-angle VSF + 4 large angle detectors
  • 50 mm optical path


  • Power input: 9 to 24 VDC
  • Sampling rate: Up to 1 Hz
  • Power drain: 120 mA / <50 mA / < 3 mA (measuring / waiting / sleeping)
  • Data storage: 1 GB (~12,500,000 size distributions)


  • Dimensions 12.6 cm (4.95”) dia. by 96.3 cm (37.9”) L
  • Weight in air / water: 18.6 kg / 9.5 kg (41 lbs / 21 lbs)
  • Weight of optional battery housing & pack in air / water: 9.9 kg / 5.4 kg (22 lbs / 11.6 lbs)
  • Maximum depth: 4,000 m (for serial numbers 4050 and higher)

LISST-Deep drawing with dimensions


LISST-Deep Item # and Description

Item #DescriptionThumbnail
SEQ-FP-LDPLISST-Deep 4000 m Sediment Size Distribution Sensor
1 um to 500 um size range
4000 m depth rating.
-1 GB of memory
-2 m communications cable
-Laser cable
-Pelicase with custom foam cushioning.
-Includes Windows software for programming, data offload and data analysis.
NOTE: The LISST-Deep is designed for external power only. It has no internal batteries.
External Battery Housing for LISST-Deep available separately.
*Must order power cable separately.
LISST-Deep promo photo
Must be purchased together with new instrument.
No picture
One-time service of instrument within 36 months after delivery.
Includes one-way return shipping from Sequoia, all evaluation, diagnosis, testing and calibration.
Parts and labor for repairs not included.
Must be purchased together with new instrument.
NOTE: End-user responsible for return shipment DDP to Sequoia.
No picture

LISST-Deep Accessories *NOT INCLUDED* with LISST-Deep

Item #DescriptionThumbnail
SEQ-AC-LDP-EBPExternal battery housing for LISST-Deep
Depth rating 4000 m. One installed and one spare LISST-Deep battery (SEQ-AC-LDP-BAT). Includes stands, clamps and cables for connecting to LISST-Deep.
Ships in Pelican case with custom foam cushioning.
LISST-DEEP External Battery Pack and Shipcase
Replacement 2 m cable with Impulse AG206-FS on each end wired pin to pin. Used to connect LISST-Deep to SeaBird CTD Auxiliary input with Impulse AG-306-HP-SS bulkhead connectors.
SEQ-AC-LDP-BATReplacement alkaline battery for LISST-Deep
12 V. Non-rechargeable.
LISST-Deep Battery
SEQ-AC-LDP-FRMLISST-Deep frame for easy integration into CTD frame.COMING!

LISST-Deep Accessories *INCLUDED* with LISST-Deep

Item #DescriptionThumbnail
SEQ-AC-LDP-BCS50 cm cable to external battery housing.
SEQ-AC-LDP-LCBLReplacement LISST-Deep Laser Cable
Replacement 0.65 m cable with Impulse MCIL-6-FS on each end wired pin to pin with locking sleeves. Used to connect laser end of LISST-Deep to electronics end of LISST-Deep.


Can I rent the LISST-Deep?

Yes. Sequoia has a rental unit available. The minimum rental period is one (1) month and the first month’s rent must be prepaid in full before the instrument is delivered. Subsequent months are invoiced at net 30 days payment terms. User must pay for the return shipping to Sequoia, and insure the instrument for the full price for the duration of the rental period as well as the return shipping.

If you decide to purchase a new instrument within 90 days after the beginning of the rental period, you can apply 85% of what you already paid in rental fees towards the cost of the new instrument.

Call for a draft rental agreement.

How does the LISST-Deep differ from the LISST-200X?

Apart from the obvious differences in the mechanical design, the LISST-Deep differs from the LISST-200X mainly with respect to available accessories. For the LISST-Deep, only a frame and an optional external battery housing are available.

Is there a BioBlock option for the LISST-Deep?

No. Sequoia does not offer a BioBlock option for the LISST-Deep.