YSI EXO2 Multiparameter Sonde

High-Quality Data Sonde for Unattended Monitoring

EXO2 is a Multiparameter Water Quality Sonde with 7 sensor ports (including a central wiper port), optional depth sensor, and battery compartment

EXO Multiparameter Sondes — the best-in-class platform for the highest quality data. EXO's dynamic range of smart sensors provide comprehensive multiparameter water quality data while SmartQC ensures proper calibrations and top sensor performance. You can be confident in your extended deployments thanks to EXO's tough materials and unmatched anti-fouling technology.

System Overview
The EXO advanced water quality monitoring platform includes the versatile multiparameter EXO2 sonde for oceanographic, estuarine, or surface water applications.

Key Benefits

exo multiparameter sonde data datasonde

Highest Data Quality
Onboard monitoring systems verify sensor operation

Multiparameter Monitoring
7 universal ports for allow for any combination of smart sensors or the central wiper

exo anti-fouling antifouling

Industry-leading Anti-fouling
Best-in-class wiper technology

Titanium Components
The toughest grade parts guarantee operation well into the future 

Seamless Integration
EXO can plug-and-play into marine, estuarine, freshwater, and groundwater monitoring systems


• Battery compartment & large memory for long-term, unattended deployments
• All sensors are field-replaceable and hold their own calibration
• Compatible with real-time data logging systems

Smart Sondes and Sensors
EXO is an extremely versatile instrument for unattended monitoring, allowing the user to automatically configure a sonde with different sensors for different applications in minutes

Smart Sensor Options:
• Conductivity/Temperature (wiped and non-wiped)
• Dissolved Oxygen
• fDOM
• ISEs (AmmoniumChloride, and Nitrate)
• NitraLED (UV Nitrate)
• pH (guarded and unguarded)
• pH & ORP (guarded and unguarded)
• Rhodamine
• Total Algae (Chlorophyll + Phycocyanin and Phycoerythrin)
• Turbidity

Other Available Parameters
• Absolute Pressure
• Ammonia
• Depth
• DO% Local
• Guage Pressure
• nLF Conductivity
• Resistivity
• Salinity
• Specific Conductivity
• Total Dissolved Solids
• Total Suspended Solids
• Water Density

EXO sondes and sensors are tested in a variety of rigorous field conditions as well as lab conditions to ensure accuracy and response times.

Monitor without Interruption
No matter which EXO sensors users select, other features of the smart sensor design make them rugged and durable:
• Wet-mateable connectors resist corrosion
• Isolated components prevent short circuits
• Welded housings and double o-rings prevent leaks
• High-impact plastic and titanium resists breaking
• Built-in anti-fouling systems protect data integrity
• Low power consumption extends underwater deployments

Monitoring Made Mobile
EXO makes it easy to view data in the field. The EXO Handheld offers a dedicated, streamlined interface to EXO sondes. EXO GO uses Bluetooth to connect any Windows OS device to a submerged EXO sonde.

Other EXO Sonde Options
• EXO2s Sonde offers the same features as the EXO2, but without the battery compartment
• EXO1 Sonde (4 ports) — also available without battery compartment
• EXO3 Sonde (5 ports including Central Wiper port) — also available without battery compartment



SKU: 599502-00

Depth / Pressure Rating / Limit 0 to 250 m (0 to 820 ft)
Desktop Software Compatible Yes
Flow Cell Yes
Languages German, English, French, Japanese, Chinese, Spanish
Logging Capabilities Yes
Medium Fresh, sea or polluted water
Memory >1,000,000 logged readings, 512 MB total memory
Monitoring Yes
Multiparameter Yes
Operating Temperature -5 to +50°C
Power 4 Alkaline Batteries
Sampling Yes
Smart Sensors / Ports Yes
Storage Temperature -20 to +80°C
Unit of Measure Parameter Dependent
User Calibratable Yes
Waterproof Yes
Battery Life 90 days*
Communications Computer Interface: Bluetooth wireless technology (between sonde and handheld or computer with KOR software), USB
Output Options: USB with signal output adapter (SOA); RS-232 & SDI-12 with DCP-SOA.
Diameter 7.62 cm (3.00 in)
Length 71.10 cm (28.00 in)
Peripheral Ports 1 power communication port; 1 auxiliary port for third-party sensors (future functionality; not active yet)
Sample Rate Up to 4 Hz
Sensor Ports 7 (6 ports available when central wiper used)
Warranty: 3 yrs Sonde; handheld
Warranty: 2 yrs Cables; conductivity/temperature and optical sensors; electronics base for pH, pH/ORP, ammonium, chloride, and nitrate sensors
Warranty: 1 yr Optical DO cap and replaceable reagent modules for pH and pH/ORP sensors
Warranty: 3 mos Replaceable reagent modules for ammonium, chloride, and nitrate sensors
Weight 3.60 kg (7.90 lbs)
*Typically 90 days at 20C at 15-minute logging interval; temperature/conductivity, pH/ORP, DO, total algae, and turbidity sensors installed with central wiper that rotates once per logging interval on EXO2. Battery life is heavily dependent on sensor configuration.

(freshwater only) Ammonium Sensor
Ammonia with pH sensor
SKU: 599710 0 to 200 mg/L (0 to 30C) ±10% of reading or 2 mg/L-N, w.i.g. T63<30 sec 0.01 mg/L
Barometric Pressure Integral Barometer 375 to 825 mmHg ±1.5 mmHg from 0 to 50°C - 0.1 mmHg
Blue-green Algae,
Phycocyanin Total Algae Sensor
SKU: 599102-01
0 to 100 μg/L;
0 to 100 RFU; Linearity: R2 >0.999 for serial dilution of Rhodamine WT solution from 0 to 100 μg/mL BGA-PC equivalents T63<2 sec 0.01 μg/L;
0.01 RFU
Blue-green Algae,
Phycoerythrin Total Algae Sensor
SKU: 599103-01
0 to 280 μg/L;
0 to 100 RFU; Linearity: R2 >0.999 for serial dilution of Rhodamine WT solution from 0 to 280 μg/mL BGA-PE equivalents T63<2 sec 0.01 μg/L;
0.01 RFU
(freshwater only) Chloride Sensor
SKU: 599711 0 to 18000 mg/L-Cl (0 to 30C) ±15% of reading or 5 mg/L-Cl, w.i.g. T63<30 sec 0.01 mg/L
Chlorophyll Total Algae Sensor
SKU: 599102-01, 599103-01
0 to 400 μg/L Chl;
0 to 100 RFU Linearity: R2 >0.999 for serial dilution of Rhodamine WT solution from 0 to 400 μg/L Chl a equivalents T63<2 sec 0.01 μg/L Chl;
0.01 RFU
Conductivity1 Conductivity / Temperature Sensor
SKU: 599870 0 to 200 mS/cm 0 to 100: ±0.5% of reading or 0.001 mS/cm, w.i.g.;
100 to 200: ±1% of reading T63<2 sec 0.0001 to 0.01 mS/cm (range dependent)
Depth - 10 m Integral, Non-vented Depth Sensor3 0 to 10 m
(0 to 33 ft) ±0.04% FS (±0.004 m or ±0.013 ft) T63<2 sec 0.001 m (0.001 ft)
Depth - 100 m Integral, Non-vented Depth Sensor3 0 to 100 m
(0 to 328 ft) ±0.04% FS (±0.04 m or ±0.13 ft) T63<2 sec 0.001 m (0.001 ft)
Depth - 250 m Integral, Non-vented Depth Sensor3 0 to 250 m
(0 to 820 ft) ±0.04% FS (±0.10 m or ±0.33 ft) T63<2 sec 0.001 m (0.001 ft)
Dissolved Oxygen, % air saturation Optical Dissolved Oxygen Sensor
SKU: 599100-01 0 to 500%
air saturation 0 to 200%: ±1% of reading or 1% saturation, w.i.g.;
200 to 500%: ±5% of reading 4 T63<5 sec5 0.1% air saturation
Dissolved Oxygen, mg/L Optical Dissolved Oxygen Sensor
SKU: 599100-01 0 to 50 mg/L 0 to 20 mg/L: ±0.1 mg/L or 1% of reading, w.i.g.;
20 to 50 mg/L: ±5% of reading 4 T63<5 sec5 0.01 mg/L
(CDOM) fDOM Sensor
SKU: 599104-01 0 to 300 ppb Quinine Sulfate equivalents (QSU) Linearity: R2 > 0.999 for serial dilution of 300 ppb QS solution
Detection Limit: 0.07 ppb QSU T63<2 sec 0.01 ppb QSU
Level, Vented - 10 m Integral Vented Level Sensor 0 to 10 m (0 to 33 ft) ±0.03% FS (±0.003 m or ±0.010 ft) T63<2 sec 0.001 m (0.001 ft)
(freshwater only) Nitrate Sensor
SKU: 599709 0 to 200 mg/L-N (0 to 30C) ±10% of reading or 2 mg/L-N, w.i.g. T63<30 sec 0.01 mg/L
pH pH Sensor
SKU:599701 guarded, 599702 unguarded

pH/ORP Sensor
SKU:599705 guarded, 599706 unguarded 0 to 14 units ±0.1 pH units within ±10C of calibration temp;
±0.2 pH units for entire temp range7 T63<3 sec8 0.01 units
ORP pH/ORP Sensor
SKU:599705 guarded,
599706 unguarded -999 to 999 mV ±20 mV in Redox standard solution T63<5 sec6 0.1 mV
Temperature Conductivity / Temperature Sensor
SKU: 599870 -5 to 35°C
35 to 50°C ±0.01°C2
±0.05°C2 T63<1 sec 0.001 °C
Turbidity9 Turbidity Sensor
SKU: 599101-01 0 to 4000 FNU, NTU 0 to 999 FNU: 0.3 FNU or ±2% of reading, w.i.g.;
1000 to 4000 FNU: ±5% of reading10 T63<2 sec 0 to 999 = 0.01 FNU, NTU;
1000 to 4000 = 0.1 FNU, NTU
Salinity Calculated from Conductivity and Temperature11 0 to 70 ppt ±1.0% of reading or 0.1 ppt, w.i.g. T63<2 sec 0.01 ppt
Specific Conductance Calculated from Conductivity and Temperature11 0 to 200 mS/cm ±0.5% of reading or .001 mS/cm, w.i.g. - 0.001, 0.01, 0.1 mS/cm
Total Dissolved Solids (TDS) Calculated from Conductivity and Temperature11 0 to 100,000 mg/L
Cal constant range
0.30 to 1.00
(0.64 default) Not Specified - Variable
Total Suspended Solids (TSS) Calculated from Turbidity and user reference samples 0 to 1500 mg/L Not specified T63<2 sec Variable
**Specifications indicate typical performance and are subject to change. All sensors have a depth rating to 250 m (820 ft), except shallow and medium depth sensors, ammonium, chloride, and nitrate. Accuracy specification is attained immediately following calibration under controlled and stable environmental conditions. Performance in the natural environment may vary from quoted specification.
w.i.g. = whichever is greater

EXO sensors are not compatible with YSI 6-Series sondes, sensors, or handheld.

1Outputs of specific conductance (conductivity corrected to 25C) and total dissolved solids are also provided. See Calculated Parameters and footnote 11.
2 Temperature accuracy traceable to NIST standards
3Accuracy specifications apply to conductivity levels of 0 to 100,000 μS/cm.
4 Relative to calibration gases
5 When transferred from air-saturated water to stirred deaerated water
6 When transferred from water-saturated air to Zobell solution
7Within the environmental pH range of pH 4 to pH 10.
8On transfer from water-saturated air to rapidly stirred air-saturated water at a specific conductance of 800 μS/cm at 20C; T63<5 seconds on transfer from water-saturated air to slowly-stirred air-saturated water.
9 Calibration: 1-, 2-, or 3-point, user-selectable
10 Performance based on 3-point calibration done with YSI AMCO-AEPA standards of 0, 124, and 1010 FNU. The same type of standard must be used for all calibration points.
11 Values are automatically calculated from conductivity according to algorithms found in Standard Methods for the Examination of Water and Wastewater (Ed. 1989).

Xenoy is a trademark of SABIC Innovative Plastics IP BV.

EXO Bluetooth modules comply with Part 15C of FCC Rules and have FCC, CE Mark and C-tick approval. Bluetooth-type approvals and regulations can be country specific. Check local laws and regulations to insure that the use of wireless products purchased from Xylem are in full compliance.

Introducing EXO - a New, State-of-the-art Water Monitoring Platform