YSI EXO3s: The Latest in Water Quality Monitoring

By on October 10, 2022
Environmental scientist, Emily Holliday, sampling water with the YSI EXO3s at the Fondriest Environmental Inc., Field Station Environmental scientist, Emily Holliday, sampling water with the YSI EXO3s at the Fondriest Environmental, Inc. Field Station (Credit: Emma Jones / Fondriest Environmental, Inc.)

The YSI EXO3s offers the latest in multi-parameter water quality monitoring equipment that has a comprehensive list of smart sensors. With an external power source, this sonde is a cost-effective, compact EXO that has the same capabilities as the EXO3. The sonde is built to last with resilient materials and backed with vigorous testing.

The device has five ports for available YSI EXO smart sensors or central wiper. It seamlessly integrates with a data logger to collect and push valuable data to the cloud for access from a PC or mobile device. This small sonde is exceptional for both sampling and continuous monitoring applications. The EXO3s ships with a probe guard, removable bail, maintenance kit, calibration and storage cup, and a USB drive that contains the KOR software to manage the EXO3s.

Latest Sensor Technology with a Long List of Parameters

The five ports on the EXO3s allow for an array of smart sensors or a central wiper, providing the flexibility to configure the unit for various projects. Turbidity, temperature/conductivity, pH and dissolved oxygen, along with a central wiper, are the most common configuration. The sonde can also be equipped with a depth sensor. With a variety of sensors to choose from, the YSI EXO3s is a customizable unit that gathers the data needed. Available sensors include:

Smart SensorParameters
Temperature and ConductivityTemperature, Resistivity, Specific Conductivity, Salinity, Non-linear function (nLF) Conductivity, Water Density, Total Dissolved Solids
TurbidityTurbidity, Total Suspended Solids
Dissolved Oxygen (DO)DO%, DO% Local
Total Algae for FreshwaterPhycoerythrin, Chlorophyll
Total Algae for SaltwaterPhycocyanin, Chlorophyll
Fluorescent Dissolved Organic Matter (fDOM)
Dissolved Organic Matter
UV Nitrate
pH and Oxidation-reduction Potential (ORP)pH, ORP
Ammonium: ion-selective electrodes (ISEs)Ammonium
Chloride: ISEsChloride
Nitrate: ISEs

Field Replaceable Sensors

Sensors are made of titanium with wet-mate connectors. The standardized sensor ports allow sensors to be swapped or replaced quickly with a newly calibrated one to ensure quality data. Each YSI smart sensor is embedded with a microprocessor and stores the calibration within the probes themselves, allowing the user to calibrate multiple sensors and disperse them to other sondes in the field.

PC Software and Handheld Display

YSI sondes are calibrated and maintained using YSI’s KOR software via Bluetooth or USB adapter. The software platform is used to maintain water quality data and manage YSI instruments. Each EXO sonde comes with a USB drive that contains the KOR software needed to calibrate sensors, manage deployment settings, and update the instrument’s firmware. Users can also view live and recorded data in graphs or table forms with YSI’s KOR software. The software helps guide the user through the process during calibrations, creating deployment templates, and updating settings on the EXO3s.

Similar to the KOR software, the EXO handheld display can calibrate the EXO3s, prepare the device for deployment, view live data, and log data in the field. The handheld is equipped with GPS and has the ability to tag up to 100 locations. Additionally, the color display on the handheld makes it easy to read in the sunlight while out in the field sampling. The handheld has a powerful built-in rechargeable lithium-ion battery that can last around 15 hours before charging,  for extended fieldwork. Using the handheld and EXO3s makes gathering high-quality data from tough spots simple.

Compact and Lightweight

Approximately 30% smaller and lighter than the EXO3, this compact sonde is ideal for spot sampling with an EXO handheld, deployment on a data collection platform or as an accessory on data buoys, AUVs, and drone systems. The small and lightweight EXO3s can be utilized in applications where the EXO3 was too large.

Spot Sampling Applications

The EXO3s is lightweight and compact and is perfect for spot sampling with the EXO handheld. Spot sampling provides a quick representation of the current state of the environment. The sonde is easy to carry to a remote sampling site for data collection. With the smaller-sized unit, sampling from a boat, in-stream, or from a bridge is more manageable.

YSI EXO3s with sensors attached

YSI EXO3s with sensors attached (Credit: YSI)

Proven Reliability and Built to Last

The EXO3s is constructed with high-quality materials to ensure a long-lasting, durable sonde. The EXO3s sondes and sensors have been tested rigorously in different field and lab conditions to produce accurate and better data, regardless of the environment. The sensors are made with titanium, so they are able to withstand harsh field conditions. The central wiper cleans the sensors and ensures high-quality data during long deployments. With wet-mateable plugs, double o-rings, isolated components, and welded housing to prevent water damage, the EXO3s is built for the toughest environments.

For extended deployments, there are different types of antifouling accessories to suit individual sampling needs. The central wiping system keeps sensors clean and measurement ready. The EXO Anti-fouling C/T Screen is a copper mesh that helps keep a barrier between the organisms and the EXO Conductivity and Temperature Smart Sensor. There is also anti-fouling copper tape, antifouling C-Spray, and an EXO3 anti-fouling guard to protect the water quality sonde and sensors.

Industry-Leading Specifications and Warranty

With the built-in serial data interface at 1200 baud (SDI-12), the EXO3s connects easily to a wide array of data loggers and telemetry systems, including NexSens Technology, Sutron, Campbell Scientific and others. SDI-12 protocol allows the EXO3s to communicate with the data logger to pass along the collected data to be stored. Once stored in the data logger, the user can then retrieve data by connecting to the data logger directly or through various modes of wireless communications.

The EXO3s specifications allow this sonde to stand out from the rest. The multi-parameter unit is equipped with a depth sensor that can measure to depths of 250 meters. The sonde comes standard with a three-year warranty, and sensors and cables have a one or two-year warranty. The EXO3s has 512 MB of total memory, so it can store >1,000,000 logged readings. Having the ability to collect a large amount of data means longer deployments and a better representation of the environment being sampled.

Environmental IoT

Internet of Things (IoT) is the connection or communication between sensors, software, or other types of technologies to each other over the internet. Environmental IoT is used to stay ahead of emergencies and system malfunctions, minimize site visits or sampling trips, and allows the user to receive easy-to-assess data quickly. Having readily available information is great for researchers to gather high-quality data at ease and to have accurate information instantly. Environmental IoT is critical for early warning systems and can alert to warning signs for floods or other natural disasters; time-sensitive data collection; or staying above/under a certain concentration limit.

When used with the NexSens Technology, WQData LIVE cloud-based datacenter, EXO3s data is quickly accessible on a laptop or desktop computer or any connected mobile device. WQData LIVE facilitates collaboration among multiple people on the same team who need the same important information quickly.

Environmental IoT allows essential data for the environment, research, or project to be obtained instantly. Having the EXO3s and smart sensor technology to measure essential parameters for early warning alerts is critical to allow researchers to forecast the intensity and duration of harmful algal blooms (HABs). The alerts also help industries monitor different water sources to prevent potential contamination, and for scientists to stay ahead of natural disasters. Environmental IoT has improved water monitoring and the ability to share information rapidly.

photo of the YSI EXO3s

YSI EXO3s (Credit: YSI)

Open Water Buoy-Based Applications

The EXO3s can be attached to a buoy for open-water applications and is commonly done for longer sampling deployments. Some different open water applications are for limnology studies, turbidity dredge monitoring and construction, HABs detection, harbor and ports monitoring, or coral reef restoration and monitoring. The open water setup allows for continuous data collection to get the best portrayal of the selected environment during different scenarios.

Fondriest Environmental Field Testing Analysis

In order to test the durability and accuracy of the YSI EXO3s, environmental scientists at Fondriest performed a quality check of the sonde at the Fondriest Environmental Field Station. Getting the EXO3s together and installing the different sensors in preparation for calibration and deployment was simple. Using manual and KOR software, calibrating the various sensors was quick and easy. WQData LIVE allowed easy access to data from the EXO3s to make sure the unit was working properly and accurately. Once the sonde was back out of the water and dried off, it was easily carried back in the convenient YSI soft-sided carrying case.

When purchasing the EXO3s and sensors, the sensors are generally not installed or calibrated. However, when buying from Fondriest Environmental, this service is offered at no additional charge. Fondriest Environmental also offers the option to rent the EXO3s for any short or long-term project. Overall, YSI EXO3s has an abundance of unique features that provides a wide variety of ways to compose a multi-parameter water quality monitoring unit that can be used for any project.

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