Water Quality

YSI offers a variety of sondes designed to meet your monitoring objectives. Selecting the right model can be time consuming and confusing. Let our knowledgeable staff assist you in selecting the model that best meets your needs.

Some of our recommendations:

EXO 1 & 2

The EXO platform is the latest in multi-parameter water quality sondes! Built for spot sampling and rugged enough for continuous monitoring, there are several new features that make sampling simple and easy. High-accuracy smart sensors with an auto-recognition feature store their calibrations, and universal fittings allow you to configure the sonde however you like. You can now calibrate sensors in the lab, remove them from your sonde and then plug & play with another sonde already in the field. Fast response time for profiling and sampling and depth sensor lets you know exactly where the sonde is during the profile. On board memory in the sonde can store over 1,000,000 readings. The handheld can record over 2,000,000 readings that can quickly and easily be downloaded via a military-grade waterproof USB port. With over 90 days of battery-life (at 15-minute intervals), central wiper, anti-fouling accessories, and easy hook-up via a flying-lead cable to a datalogger, the EXO2 is perfect for long-term unattended and continuous monitoring assignments.

The EXO platform offers the following unique and useful features:

  • User-replaceable digital “smart” sensors with wet-mateable, corrosion-resistant connectors
  • Isolated components prevent short circuiting
  • Laser-welded titanium sensor housing with double O-rings to prevent leaks
  • High-impact plastic and titanium resists breaking and corrosion
  • Low power consumption extends underwater deployments
  • Large memory can store over 1 million logged readings
  • Work in depths up to 250 m (820 feet)
  • Internal barometer allows for quick precise DO calibration
  • Accurate depth sensor (10, 100, 250 m) provides precise profiling data
  • KorDSS software (included) and a USB on-the-go connector assist with data management

Choose from among the list of available probes, plug into any of EXO port, and start collecting data! The EXO1 has 4 ports while the EXO2 has 6 ports plus a port for the central wiper.

  • Conductivity/Temperature
  • Optical Dissolved Oxygen
  • pH or combination pH/ORP
  • Total Algae (Chlorophyll + Blue Green Algae)
  • Turbidity
  • Fluorescent Dissolved Organic Matter (FDOM)

There are many customizable options with the EXO 1 & 2. Contact us to help you select the model and accessories that will meet all of your monitoring needs.

Professional Series

The Professional Series offers several meter/probe combinations designed to fit a wide range of parameter combinations and price points. Let us walk you through the process or use our handy chart to find the model that works best for you.

We’ve highlighted our most popular Pro Series instruments – ProDSS, Quatro, and ProODO.

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The YSI ProDSS (Digital Sampling System) Handheld multi-parameter meter provides extreme flexibility for the measurement of Optical Dissolved Oxygen, Turbidity, Conductivity, Specific Conductance, Salinity, Resistivity, Total Dissolved Solids (TDS), pH, ORP, Temperature, along with an optional depth sensor. Titanium, “smart” probe technology allows for any combination of probes and no assigned ports. Calibration history is stored inside the probe. Even if the probe switched between devices, its individual calibration is easily found. This professional quality equipment will meet your monitoring needs today and can be adapted for projects into the future.

Multiple features include:

  • User-replaceable, digital smart sensors are automatically recognized by the instrument and store calibration data
  • Internal barometer allows for quick precise DO calibration
  • KorDSS software (included) and a USB on-the-go connector assist with data management
  • Rechargeable lithium-ion battery; ensures reliability and minimizes waste
  • Color display with menu-driven operation and backlit keypad
  • Optional GPS
  • Optional Depth sensor and up to 100-m cable length
  • Large Memory (>100,000 data sets) with extensive site list capabilities
  • Military spec connectors, waterproof IP67 rating and rubber over-molded case
  • 3-year instrument warranty; 2-year cable warranty (sensor warranties vary)

Professional Plus Quatro

The YSI Professional Plus handheld multi-parameter meter provides extreme flexibility for water quality monitoring. The Quatro has four ports available for the measurement of Dissolved Oxygen (Polarographic or Galvanic), Conductivity, Specific Conductance, Salinity, Resistivity, Total Dissolved Solids, pH, ORP, and Temperature.

Features include:

  • Internal barometer allows for quick precise DO calibration
  • 5,000 data set memory
  • User-replaceable sensors and a choice of Polarographic or Galvanic DO sensors
  • Laboratory grade ISE sensors and BOD probe available
  • Detailed on-screen Help function
  • Multiple cable options available up to 100 meters
  • Wide array of accessories from flow cells to carrying cases
  • USB and commination saddle along with Data Management software included
  • Military spec connectors, waterproof IP67 rating and rubber over-molded case
  • 3-year display warranty; 1-year cable and probe warranty


The YSI ProODO Optical Dissolved Oxygen meter utilizes the optical technology to measure dissolved oxygen. The ProODO instrument meets the demands of true field work. The instrument is waterproof and rated to IP-67 standards even without the battery cover in place. Free software makes data management simple and efficient and allows you to download data, configure instruments, and conduct real-time studies easily. View data graphically or in tabular form and export data as needed to other programs such as Excel.

Features include:

  • Internal barometer allows for quick precise DO calibration
  • 5,000 data-set memory
  • Laboratory Optical BOD – self-stirring BOD probe
  • Expanded DO range of 0-500% (0-50mg/L)
  • Detailed on-screen Help function
  • Multiple cable options available up to 100 meters
  • USB and commination saddle along with Data Management software included
  • Military spec connectors, waterproof IP67 rating and rubber over-molded case
  • 3-year instrument warranty and 1-year cable and probe warranty

Model 550A Dissolved Oxygen Meter

Looking for a rugged, field-worthy instrument for measuring dissolved oxygen? The YSI 550A Dissolved Oxygen meter features a waterproof IP-67, impact resistant case and an innovative field-replaceable DO electrode module. Measure temperature and dissolved oxygen simultaneously using highly accurate thermistors and YSI’s proven polarographic DO technology and features automatic salinity and altitude compensation. Measurements are fast and easy with one-handed operation, an easy to use backlit display, automatic push-button calibration, and a weighted, quick sinking probe.

The Model 550A features screw-on cap membranes that make membrane changes easier than ever. The PE membranes respond faster and require much less flow than traditional membranes. The user-replaceable DO module decreases down time. Simply unscrew the old electrode, replace it, and calibrate! No need to send it in or to replace the whole cable assembly.  The meter comes with a 3-year warranty along with 1 year on the cable and probe.

Interested in Dissolved Oxygen? Take a look at YSI Professional Series products – Pro20 and ProODO Optical DO handheld meters. Let us help you find the perfect meter for your application.

Interested in Dissolved Oxygen? Take a look at YSI Professional Series products – Pro20 and ProODO Optical DO handheld meters. Let us help you find the perfect meter for your application.

Model 9300 and 9500 Photometer

Measuring the desired parameter has never been easier! Simply choose among the list of available tests on the large graphic display and the instrument will walk you through the test procedure – it’s that easy! Simple. Convenient. Accurate.

Features include:

  • Direct reading concentrations
  • Waterproof IP-67 rating
  • Large, backlit graphic display
  • Sample tube holder automatically adjusts for various diameters
  • On-screen instructions virtually eliminates reading manuals
  • 100+ test choices

In addition, the 9500 features:

  • Waterproof USB connection that can also power the instrument
  • Internal memory for 500 sample sets
  • User-selectable options for test units, sample numbers, dilutions factors, or additional tests

Both the 9500 and the 9300 include a hard-sided carrying case with foam cutouts for the instrument, accessories, reagents and more.

EcoSense – DO, pH, Conductivity/Temp Meters

Okay, we get it. Sometimes your budget won’t allow for a premium instrument with more features but you still need a basic instrument to do your job without sacrificing data quality. Our EcoSense line of products is simple, easy to use, and straight-forward. And hey they still have some pretty good features!

  • Large displays
  • Quick calibrations 50 data-set memory
  • Watertight case meets IP67 specs
  • Submersible waterproof cables
  • 1-year instrument warranty

Just want reliable, precise data? Check out our consulting pages, and let us be a part of your team.


Need instantaneous Flow? Check out the FlowTracker for wadeable measurements and the RiverSurveyor for non-wadeable systems

Need continuous flow? We recommend the SonTek IQ or SL systems. Every site is different, we will gladly help you determine which system would work best for you!

These are our favorites! Contact us directly and we will gladly help find the equipment needed for your specific project and goals.

Our Top Four SonTek products:

RiverSurveyor ® S5 and M9

“Patented and award winning systems give a new perspective to measure open channel Hydraulics”

Simple, durable, portable but with an amazing level of detail and accuracy; the RiverSurveyor makes bathymetry, surveying and streamflow measurements quick and simple. Spend less time at on site and collect higher resolution data! Differential and RTK GPS options are available for moving bed and surveying applications. This is a system that will adjust and work in just about any environment that you put it in. Mount it on a boat or use our functional Hydroboard to run precise transects. There is so much more this system can do; let us design the perfect system for your needs.

  • SmartPulseHD® Multi-Band acoustic frequencies
  • Vertical acoustic beam
  • Internally computed discharge and secure data
  • Standard 360◦ compass with two-axis tilt sensor
  • Reverberation control with ping rates to 70Hz
  • Bottom-tracking
  • Differential or RTK GPS (optional)

FlowTracker2® Handheld-ADV®

The FlowTracker2 (FT2) handheld Acoustic Doppler Velocimeter (ADV®) has all the technology you have grown to know and trust with the original FlowTracker, but now comes with functional, modernized features including Bluetooth, GPS and a large color screen at the request of hydrologists, researchers and scientists who have made the FlowTracker their instrument of choice. Get defensible data correctly, the first time, every time, and minimize data handling back at the office. Each step of the way FT2 guides you along the measurement process with visual prompts and SmartQC audio alerts just in case something important needs your attention. FT2 handheld software is intuitive, easy to navigate and includes real-time plots of point data, QC parameters, and measurement verticals, giving you everything you need at-a-glance.
Some of the major improvements come straight from field users like you:

  • Embedded GPS for georeferencing with automatic or manual fixes
  • Improved ADV acoustics: faster pinging, lower noise and better standard error
  • Battery life icon on the screen at all times.  Pre-load the spare cartridge and replace, even mid-measurement, with no data loss
  • Detachable probe with extension cables to customize cable length up to 10m
  • Probes and handhelds are interchangeable—flexibility within agency teams and when sending equipment for service
  • Set up and save templates—no need to re-enter data every time you visit a site
  • Bluetooth or direct USB interface with PC
  • Audio prompts

At its core, FT2 uses SonTek’s tried-and-true ADV technology, vetted for decades by experts across the globe, in hydraulics labs and wide-ranging field environments.  Improved and perfected for FT2, the acoustic-based ADV sensor offers unparalleled accuracy, particularly in low flow, and in the shallowest water of any wading device.  2-D data in the horizontal plane (2D/3D option available) allows the most comprehensive QC and understanding about flow conditions, and user calibration is never required.

SonTek® –SL Series

“A simple way to measure water velocity and level in open channels”

This long-term monitoring device combines the SmartPulseHD® technology to allow for precise and simple monitoring. Designed for side mounting on bridges, canals, and riverbanks small enough to jump across or as large as 120-m (400ft). Its compact design is very lightweight easy to install and maintain with customizable setup can for a variety of applications and includes high resolution and detailed profiles. Water level is measured with a vertical acoustic beam. Its low profile and side monitoring allows for minimal disturbance and limits interruptions from divers, boats, and facility operations. Pair with a datalogger and you could drive up and check flow from your car or transmit the data to the web for real time data in your office.

  • Water velocity, level, flow and total volume parameters from one instrument
  • SmartPulseHD® intelligent algorithm acoustically adapts to changing conditions provide the best possible data under any condition
  • Compact, Hydrodynamic Design
  • Water Velocity Profiling with customizable and flexible setup to allow for a variety of techniques
  • Acoustic-pressure “Duo” Water Level (3G models only) continuously self-checks and adjusts height to offset atmospheric changes
  • Versatile, easy mounting with easy side access
  • Wave spectra option calculates wave-height and period in real time
  • Standard package includes SonTek-SL, SL software, and 10-m cable

SonTek-IQ® Series

“Ideal for Monitoring flows in canals, culverts, pipes and natural streams”

Low profile, high data quality. Built for monitoring flows in canals, culverts, pipes and natural streams. Vertical beam reads changing water levels and SmartPulseHD technology adjusts beam distance to ensure you are receiving the more precise and accurate data available. This small and durable meter allows you to collect flow data in minutes. IQ Pipe is specifically designed for placement in full or non-full pipes and culverts where water level may change or is irregular and includes enough internal storage for 1-year of monitoring, depending upon settings. Pair with a datalogger and you could drive up and check flow from your car or transmit the data to the web for real time data in your office.

  • Self-contained all-in-one design
  • Proprietary flow algorithms for irrigation, canals, natural streams and pipes
  • Uses SonTek’s exclusive SmartPulseHD adaptive sampling
  • Self-calibrating water level using vertical acoustic beam and pressure
  • Standard package includes SonTek-IQ, IQ software, easy mounting hardware, and 10-m cable

Just want reliable, precise data? Check out our consulting pages, and let us be a part of your team.

Telemetry, Level, and Meteorological


No more laptops in the field! Configure & download your Storm 3 data logger with drop-down graphical user interface using any standard web browser found on PCs, tablets and smart phones. The Storm 3 incorporates inputs for analog, digital I/O and a SDI-12 smart sensors to allow communication through a cellular or GOES satellite modem. You can also view your password-protected data anywhere using our cloud hosted data warehousing and webhosting solution – Storm Central. Pair Storm Central with the Storm 3 Data Logger and you’ve got one mean data-collecting machine that you can access anytime, anywhere.

  • Built-in Sensor Library for YSI, SonTek, Waterlog and other manufacturers
  • Browser-based Graphical User Interface
  • Direct or wireless connection (wi-fi antenna included)

The WaterLOG XL Series

Specifically designed to collect reliable data under extreme environmental conditions, the XL data logger series was made for serious professionals. The XL series offers a familiar interface across all four platforms (350XL, 500XL, 522 and 522 Plus). You’ll love the simplicity of the display, allowing programming and configuration without the need to hook up to a laptop. And for those of you who prefer to use a laptop, rest assured knowing we’ve made that option available, as well. Whatever your data collecting needs may be, you can rely on the XL Series for accurate, dependable data collection.

Nile Series Radar Level

New! Designed for non-contact water level measurements, the WaterLog Nile Series combines high accuracy with an out-of-the-box measurement range of up to 70 meters. The rugged innovative design was inspired for installation on a bridge or other structure over the water – making this series idea for sites that may have ice or other instrument-damaging debris. Its reliable interface and simple SDI-12 communication ensures seamless integration with current water monitoring stations. With three models to choose from, the Nile Series is sure to meet your water level measurement needs.

Other Radar Systems are available. Contact our office and let us help you decide what works best for your application.

3553T Continuous Bubble Water Level Meter

Built and tested for the most rigorous standards, the Bubbler (H-3553T) incorporates the features of earlier models and adds to them. Designed specifically for measuring fluid levels in surface water applications, groundwater and tanks, this compact combo system has a built-in calibrated pressure sensor. The continuous display provides a readout of the last measured value for quick reference.

The bubbler also has an improved controller and pressure regulator that use a sophisticated system of sensors and valves to regulate the bubble rate and purge pressure. And to keep the sediment from settling around the orifice line, this Bubbler provides a purge feature to keep the pressure at a desired level. You can even start a manual purge, anytime, with the touch of a button. This system was made for those who don’t have time to mess around at the site.

SDI-12 Rain Gauge

Whether you’re new at rain measurement technology or know the systems like the back of your hand, you’ll love the features of the SDI-12 Tipping Bucket Rain Gauge (H-3401) – such as the built-in microprocessor that automatically corrects errors. It also has a magnetic read bucket tip sensor and an internal leveling mechanism with a “bulls-eye” level to ensure high accuracy data. The Rain Gauge is available in 0.01 inch, 0.1 mm and 0.2 mm resolution ranges.

Just want reliable, precise data? Check out our consulting pages, and let us be a part of your team.