YSI is your one-stop source for environmental water quality monitoring instrumentation, offering single and multiparameter instruments, integrated systems, and accessories for most unattended monitoring, water quality sampling, profiling and logging applications. read more

YSI instruments are used in numerous applications worldwide including surface water, oceans / coastal, wastewater, storm water, food and beverage, aquaculture, source water and drinking water, ground water, laboratory, and desalination.

YSI is dedicated to providing quality data to customers and to preserving the planet's natural environment.

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YSI Professional Plus Multiparameter Meter
The toughest, smartest and most versatile water quality meter available
$1,230.00
$1,168.50
In Stock
YSI ProDSS Multiparameter Meter
Portable digital sampling system for the measurement of up to 17 water quality parameters
$1,630.00
YSI Pro20 Dissolved Oxygen Meter
Rugged, reliable DO meter that is easy to operate while featuring user-replaceable sensors and cables
$560.00
$532.00
In Stock
YSI ProODO Dissolved Oxygen Meter
Handheld, luminescent based dissolved oxygen meter for any field application
$740.00
$703.00
In Stock
YSI 9300 & 9500 Photometer
Economical photometers allow for field readings of 100+ parameters
$1,090.00
$1,035.50
YSI Pro30 Conductivity Meter
Handheld field meter for conductivity, salinity, TDS and temperature
$580.00
$551.00
YSI 5000 Series Dissolved Oxygen Meters
Highly accurate, reliable advanced instrumentation for measuring dissolved oxygen
$1,410.00
$1,339.50
YSI EcoSense DO200A Dissolved Oxygen / Temperature Meter
Accurate, economical, handheld measurements, IP67 waterproof housing
$290.00
$275.50
YSI Pro2030 Dissolved Oxygen & Conductivity Meter
Measures dissolved oxygen, salinity, conductivity, specific conductance, TDS, barometric pressure and temperature
$765.00
$726.75
YSI 3100/3200 Conductivity Meters
High accuracy, ±0.1%, conductivity measurement instruments
$945.00
$897.75
YSI Pro1030 Multiparameter Meter
Tough, smart and versatile pH/ORP/Conductivity/Salinity/TDS/Temperature meter designed for rugged field work
$765.00
$726.75
YSI pH100A EcoSense pH100A pH/ORP Meter
Accurate, economical, handheld, IP67 waterproof housing
$265.00
$251.75
In Stock
YSI EcoSense EC300A Conductivity Meter
Accurate, economical, handheld measurements, IP67 waterproof housing
$305.00
$289.75
YSI Pro1020 pH / ORP & DO Meter
Handheld meter that measures dissolved oxygen and temperature along with either pH or ORP (redox)
$760.00
$722.00
YSI EcoSense pH10 pH Tester
pH and temperature measurement in a pen-style tester with graphic display
$116.00
$110.20
In Stock
YSI Pro10 pH / ORP Meter
Portable, user replaceable sensors and cables, 50 data set memory, IP67 protection
$495.00
YSI pH1200 pH/mV Meter
Simple, accurate laboratory-grade pH, mV and temperature measurements
$545.00
$517.75
YSI EcoSense ORP15 ORP Tester
ORP and temperature measurement in a pen-style tester with graphic display
$167.00
$158.65
YSI pHotoFlex Colorimeter
Portable Colorimeters for lab and field, calibration adjustment for selected methods, multiparameters
$1,010.00
YSI 910 COD Colorimeter
Single parameter colorimeter for COD, rugged, waterproof, multi range ideal for laboratory and field testing
$565.00
YSI MultiLab 4010-3 Water Quality Instrument
Three channel input for pH, ORP, Optical-Based DO/BOD, or conductivity, antibacterial keypad, large, easy to read color display
$1,920.00
YSI 900 Chlorine Colorimeter
Single parameter colorimeter for total and free chlorine, ideal for laboratory and field testing
$395.00
YSI MultiLab 4010-1 Water Quality Instrument
Single channel input for pH, ORP, Optical-Based DO/BOD, or conductivity, large, easy to read backlit graphic display
$1,095.00
YSI MultiLab 4010-2 Water Quality Instrument
Two channel input for pH, ORP, optical-based DO/BOD, or conductivity, large, easy to read color display
$1,490.00
YSI 1201 pH/mV Electrode
pH/mV electrode with BNC connector and 1-meter cable
$57.00
$54.15
YSI TruLab pH/ISE 1320 Laboratory Benchtop Meter
Dual channel meter for dual measurement of pH, mV (ORP) or ISE, AutoRead function improves repeatability
$1,595.00
YSI ProDSS Smart Sensors
Smart sensors for use with the YSI ProDSS multiparameter meter
$450.00
YSI Calibration Solutions and Standards
Full range of calibration solutions and standards for YSI analytical meters
$33.00
In Stock
YSI ProDSS Cable Assemblies
Cable assemblies with 4 universal sensor ports and optional depth sensor
$1,740.00
YSI 20 Pro Series DO Cable
1-port cable for use with the Professional Plus instrument. The port requires a DO probe.
$250.00
$237.50
In Stock
YSI 1001 pH Sensor
pH sensor for YSI Pro Series analytical instruments
$175.00
$166.25
In Stock
YSI 2002 Galvanic DO Sensor
Galvanic dissolved oxygen sensor for YSI Pro Series analytical instruments
$185.00
$175.75
In Stock
YSI 5908 Dissolved Oxygen Cap Membrane Kit
Six-pack of 1.25 mil PE membranes with yellow caps
$60.00
$57.00
In Stock
YSI ProDSS ODO/CT Probe & Cable Assembly
Features integral (i.e. built-in) optical dissolved oxygen, conductivity, and temperature sensors and is available in lengths up to 100 meters
$840.00
YSI 5790 Pro Series Quatro Cable
4-port cable for use with the YSI Professional Plus meter. Create a powerful multiparameter sampling instrument.
$1,355.00
$1,287.25
In Stock
YSI 30 Pro Series Conductivity Cable
Allows for the measurement of conductivity, specific conductance, salinity, total dissolved solids and temperature
$325.00
$308.75
YSI 559 Replacement DO Sensor Module
Replacement DO sensor module for YSI 550A and 556 dissolved oxygen meters
$195.00
$185.25
YSI ProODO Cable and Probe
ProODO cable and probe includes ODO optical DO sensor and sensing cap
$670.00
$636.50
In Stock
YSI EcoSense pH100 pH Probes
Probes and electrodes for use with the YSI pH100 meter
$55.00
$52.25
YSI 5906 Dissolved Oxygen Cap Membrane Kit
Six-pack of 1 mil Teflon membranes with black caps
$60.00
$57.00
YSI 2003 Polarographic DO Sensor
Polarographic dissolved oxygen sensor for YSI Pro Series analytical instruments
$180.00
$171.00
In Stock
YSI Photometer Test Kits
Reagent starter kits for the YSI 9300 and 9500 photometers
$12.00
YSI 5564 & 5565 pH/ORP Probe
YSI pH/ORP probe is compatible with YSI 5563 cable assembly
$275.00
$261.25
YSI 5560 Conductivity/Temperature Probe
Combination temperature and conductivity sensor for YSI Pro Series analytical instruments
$430.00
$408.50
YSI 625120 BOD Analyst Pro Software
Easy, efficient and accurate desktop software for the caluculation of BODs
$595.00
$565.25
YSI 5010 Series Self-stirring BOD Probes
Self-Stirring BOD Probes - Classic Design for True Reliability
$680.00
$646.00
YSI 2030 Pro Series DO/Conductivity Cable
1-port combo cable for use with the YSI Professional Plus meter. The 1-port requires a DO probe while the conductivity is built right into the cable.
$625.00
$593.75
YSI 10 Pro Series ISE Cable
1-port cable for use with the Professional Plus instrument. The port requires a ISE probe.
$265.00
$251.75
YSI Hard Carrying Case
The ultimate protection for your YSI Pro Series meter
$285.00
$270.75
YSI 1004 Ammonium, NH4+ Sensor
Ammonium, NH4+ sensor for YSI Pro Series analytical instruments
$365.00
$346.75
YSI Soft Carrying Case
Organize any Pro Series meter and accessories while protecting them from the elements
$125.00
$118.75
In Stock
YSI 1030 Pro Series ISE/Conductivity Cable
Requires an ISE probe while the conductivity sensor is built right into the cable
$465.00
$441.75
YSI 3100/3200 Conductivity Cells
YSI conductivity cells with optional temperature sensor for use with YSI 3100/3200 conductivity instruments
$290.00
YSI 1020 Pro Series ISE/DO Cable
2-port combo cable for use with the YSI Professional Plus instrument. The 2-ports require a ISE and a DO probe.
$565.00
$536.75
YSI EcoSense DO200 Dissolved Oxygen Probes
Probe and cable assemblies for YSI EcoSense DO200 dissolved oxygen meter
$310.00
$294.50
YSI 5905 Series Self-stirring BOD Probes
For measuring dissolved oxygen in all popular size BOD bottles
$725.00
$688.75
YSI 1003 pH/ORP Sensor
pH/ORP sensor for YSI Pro Series analytical instruments
$295.00
$280.25
YSI 1002 ORP Sensor
ORP sensor for YSI Pro Series analytical instruments
$205.00
$194.75
YSI 1006 Nitrate Sensor
Nitrate sensor for YSI Pro Series analytical instruments
$365.00
$346.75
YSI ProODO Sensor Cap
Replacement ODO sensor cap kit for the YSI ProODO dissolved oxygen meter
$105.00
YSI Flow Cells
For applications where it is impossible or undesirable to submerge the probe module into the sample
$335.00
$318.25
YSI 5238 Dissolved Oxygen Probe Reconditioning Kit
400 grit sanding discs and sanding tool
$30.00
$28.50
YSI ProBOD Probe
Self-stirring BOD probes designed to fit into standard U.S. style 300 mL BOD bottles
$710.00
YSI 1007 Pro Series pH Sensor and Cable
Lab-grade pH sensor and 1- or 4-meter cable for the YSI Professional Plus meter
$190.00
$180.50
YSI 060906 Conductivity Standard
Conductivity standard, 1,413 uS/cm, +/- 1.0% tolerance, NIST traceable, case of eight individual pints
$124.00
YSI EcoSense EC300 Conductivity Probes
Probe and cable assemblies for YSI EcoSense EC300 conductivity meter
$250.00
$237.50
YSI 5913 Dissolved Oxygen Cap Membrane Kit for Galvanic Sensors
Six-pack of 1.25 mil PE membranes with yellow caps
$60.00
$57.00
YSI 3166 Conductance Calibrator Set
Resistor set verifies performance
$350.00
$332.50
YSI 5775 Standard Dissolved Oxygen Membrane Kit
Stretch-style 1 mil membrane including electrolyte
$40.00
$38.00
YSI 1203 pH/ATC Temperature Combination Electrode
pH/ATC temperature combination electrode with BNC connector and 1-meter cable
$150.00
$142.50
YSI 1005 Chloride Sensor
Chloride sensor for YSI Pro Series analytical instruments
$365.00
$346.75
YSI 5239 Dissolved Oxygen Probe
Rugged field DO probe with easy-to-replace cap membranes
$530.00
$503.50
YSI Thermoreactor
For COD/thermal digestions, 115V, fixed or selectable temperatures
$760.00
$722.00
YSI EcoSense pH10 Electrode
Single or double-junction pH electrodes for YSI EcoSense pH10 tester
$55.00
$52.25
YSI 5563 Cable/Sensor Assembly
Cable assembly with integral DO, temperature & conductivity sensors
$1,095.00
$1,040.25
In Stock
YSI 160 Electrode Simulator
Simulates pH 4, 7, and 10 to determine the accuracy of the YSI EcoSense pH 100 meter
$120.00
$114.00
YSI 3232 Adapter Cell
YSI 3232 Adapter Cell
$185.00
$175.75
YSI ProOBOD Probe
Self-stirring to provide a representative sample and increase response times
$955.00
$907.25
YSI 111 EcoSense Piercing pH Sensor
Double-junction, piercing tipped pH sensor with 1-meter cable
$147.00
$139.65
YSI 1010 Pro Series Dual ISE Cable
2-port combo cable for use with the YSI Professional Plus instrument. The 2-ports require ISE probes.
$565.00
$536.75
YSI 5909 Dissolved Oxygen Cap Membrane Kit
Six-pack of 2 mil PE membranes with blue caps
$60.00
$57.00
YSI 626500 IDS ProOBOD Probe
Optical Self stirrring BOD probe with temperature sensor, IDS
$910.00
YSI 1008 Pro Series ORP Sensor and Cable
Lab-grade ORP/Temperature sensor and 1- or 4-meter cable for the YSI Professional Plus meter
$200.00
$190.00
YSI 1009 Pro Series pH/ORP Sensor and Cable
Lab-grade pH/ORP sensor and 1- or 4-meter cable for the YSI Professional Plus meter
$305.00
$289.75
YSI 301710Y IDS 4310 Conductivity and Temperature Probe
Conductivity and temperature, Epoxy body, 4-graphite electrodes, digital probe, 1.5 or 3 meter cable
$360.00
YSI 5083 Flow Cell
YSI 5083 Flow Cell
$400.00
$380.00
YSI 5685 Half-Sensitivity Dissolved Oxygen Membrane Kit
Stretch-style 2 mil membrane for long-term monitoring situations
$42.00
$39.90
YSI Silica Reagent
Low, high and ultra high ranges available, pack of 100
$53.00
YSI Ammonium NH4 Reagents
Nitrogen, Ammonia, powder pack of 100, low Range vial pack of 50, high range vial pack of 50 options
$79.00
YSI 251399Y Secondary Reference Standard
Secondary Reference Standard, pack of 3, 0.0, 0.20 and 1.0 mg/L
$85.00
YSI 170 Electrode Stand
Securely holds electrodes during measurements in a lab setting
$97.00
$92.15
YSI 103740Y /103741Y IDS 4110 Probe
Combination pH and temperature, Plastic, Gel filled, digital, double junction probe, 1.5 or 3 meter cable
$225.00
YSI 103790Y IDS 4210 ORP Probe
Combination ORP, Glass , digital, double junction probe, 1.5 meter cable
$310.00
YSI LR44 Batteries
Replacement LR44 Batteries
$5.00
$4.75
YSI 480 Shoulder Strap
Convenient shoulder strap keeps your instrument close by and safe when out sampling in the field
$29.00
$27.55
YSI Nitrite Reagent
Low Range, powder, 10 ml or 25 ml, pack of 100
$31.00
YSI COD Reagents
Low range and high range vials, Hg free option, pack of 25 or 150
$36.00
YSI 380 Hard Carrying Case
Hard sided carrying case for YSI EcoSense EC300 conductivity meter
$40.00
$38.00
YSI 5011 Cable Adapter
Connects probes to YSI 5000 and 5100 Benchtop DO meters
$100.00
$95.00
YSI Nitrogen Reagent
Nitrogen, Total, vial reagent pack, pack of 50 for 25 tests
$111.00
YSI 109830Y Calibration Kit
Calibration kit for IDS pH electrode, 3 ampules: 4.01, 6.86, 9.18
$28.00
YSI Phosphate Reagent
Phosphate (Orthophosphate), powder pack reagent, pack of 100
$28.00
YSI ProDSS ODO/CT Replacement Sensor Cap
Choice of 1 or 2 year warranty ODO sensor cap for ProDSS ODO/CT probes
$102.00
YSI 400351 TruLine pH 17 Electrode
pH electrode no temperature, single-junction, combination, refillable, glass shaft with 1-m cable, BNC connector
$165.00
YSI 109813Y Stand and Holder
Stand and holder for the YSI MultiLab Line
$225.00
YSI 103780Y IDS 4120 pH and Temperature Probe
Combination pH and temperature, Glass, 3 mol KCL, digital, double junction probe, 1.5 meter cable
$325.00
YSI 251392Y Primary Standard
Primary standard, 100 mL, 1.5 mg/L
$22.00
YSI 063517 Ultra Clamp
Ultra Clamp for YSI Pro Series
$25.00
YSI 063507 Tripod
Tripod, Ideal in the lab or any other level surface
$30.00
YSI 603070 Shoulder Strap
Shoulder strap for YSI Pro Series
$31.00
YSI 180 Hard Carrying Case
Hard sided carrying case for YSI EcoSense pH100 meter
$40.00
$38.00
YSI EcoSense ORP15 Electrode
Replacement electrode for YSI EcoSense ORP15
$75.00
$71.25
YSI 3078 Flow Cell Adapter
Single port flow cell adapter for use with 603059 or 603076 flow cells
$97.00
YSI 112 EcoSense Flat Glass pH Sensor
Double-junction, flat glass pH sensor with 1-meter cable
$147.00
$139.65
YSI 103750Y IDS 4130 Probe
Combination pH and temperature, Plastic, 3 mol KCl, digital,double junction probe, 1.5 meter cable
$260.00
YSI 301720Y IDS 4320 Conductivity and Temperature Probe
Conductivity and temperature, Stainless Steel body, 2-electrodes, digital probe, 1.5 meter cable
$495.00
YSI Rochelle Salt Liquid Reagent
Rochelle Salt, liquid reagent, 30 ml or 500 ml, number of tests varies with hardness concentration
$12.00
YSI 605611 USB Cable
USB cable for connecting instrument with USB-mini B to a computer
$13.00
YSI 251416Y Hydrazine Reagent
Hydrazine, 100 mL for 50 tests, 0.004 to 0.600 mg/L
$16.50
YSI Iron Reagent
Iron, Total, Low Range, powder, pack of 100, multiple ranges
$19.00
YSI Chlorine Total Reagent Powder
Chlorine, total reagent, powder, 10 mL, pack of 100 or 1000, 0.02 to 2.00 mg/L
$20.00
YSI Chlorine Reagent Powder
Chlorine, free reagent, powder, 10 mL, pack of 100 or 1000
$20.00
YSI 605978 Cable / Probe Weight
Cable / Probe Weight, 4.9 oz, stackable, add to guard as needed to increase probe weight by 4.9 oz per piece
$27.00
YSI Sulfate Reagent
Sulfate, powder, 10 ml or 25 ml, pack of 100
$27.00
YSI 580 Soft Carrying Case
Soft carrying case YSI EcoSense pH10 and ORP15 tester
$29.00
$27.55
YSI 603069 Belt Clip
Belt Clip for Pro Series
$28.00
YSI 280 Hard Carrying Case
Hard sided carrying case for YSI EcoSense DO200 dissolved oxygen meter
$40.00
$38.00
YSI Phosphorus Reagent
Phosphorus, Reactive (Orthophosphate), vial, pack of 50
$38.00
YSI 251403Y Copper Reagent
Copper, Powder, pack of 100, 0.5 to 12.00 mg/L
$38.00
YSI 5776 High-Sensitivity Dissolved Oxygen Membrane Kit
Stretch-style 0.5 mil membrane including electrolyte
$44.00
$41.80
YSI Manganese Reagent
Manganese high Range or low range, powder, pack of 100
$43.00
YSI YPT284 Waterproof USB Cable
Replacement waterproof USB cable for the YSI 9500 photometer
$52.00
$49.40
YSI 5914 Dissolved Oxygen Cap Membrane Kit for Galvanic Sensors
Six-pack of 2 mil PE membranes with blue caps
$60.00
$57.00
YSI 5912 Dissolved Oxygen Cap Membrane Kit for Galvanic Sensors
Six-pack of 1 mil Teflon membranes with black caps
$60.00
$57.00
YSI 251993Y Nitrate Reagent
Nitrate, vial reagent, pack of 50 for 25 tests, 0.2-30 mg/L NO3-N; 1.0 - 133 NO3
$65.00
YSI 1202 Temperature Probe
Stainless steel temperature probe with 10K thermistor
$75.00
$71.25
YSI Molybate Power Pack Reagent
Molybdate, powder, 10 ml or 25 ml, pack of 100
$80.00
YSI 5793 Standard Dissolved Oxygen Membrane 10-Pack
Stretch-style 1 mil membranes including electrolyte
$88.00
$83.60
YSI 251421Y Oxygen Scavenger Reagent
Oxygen Scavenger DEHA1, powder, pack of 100 0.004 to 0.450 mg/L
$85.00
YSI 5794 High-Sensitivity Dissolved Oxygen Membrane 10-Pack
Stretch-style 0.5 mil membranes including electrolyte
$90.00
$85.50
YSI YPT283 USB Power Supply
USB power supply for the YSI 9500 photometer
$92.00
$87.40
YSI 603162 Carrying Case
Soft sided carrying case, accommodates up to a 4 meter cable
$90.00
YSI Soft Carrying Case
Soft carrying case for YSI meters
$105.00
$99.75
YSI 251400Y Aluminum Al-1 TP Powder Pack
Aluminum, powder pack reagent set with 25 ml ECR Masking liquid reagent, 100 tests
$115.00
YSI 400353 TruLine pH 25 Electrode
pH electrode no temperature, single-junction, combination, gel electrolyte, epoxy shaft with 1-m cable, BNC connector
$125.00
YSI 902867 Universal Power Supply
Universal power supply for YSI MultiLab instruments
$125.00
YSI 251300Y Rechargeable Battery
Rechargeable battery for the pHotoFlex STD and pH; STD requires Lab Station
$169.00
$160.55
YSI 4010-2/3 Adapter pH Adapter
DIN or BNC pH adapter for 4010-2/3
$175.00
YSI 400356 TruLine ORP 51 Electrode
ORP electrode no temperature, single-junction, gel electrolyte, epoxy shaft with 1-m cable, BNC connector
$175.00
YSI 400352 TruLine pH 26 Electrode
pH electrode with temperature, single-junction, 3 in 1, gel electrolyte, epoxy shaft with 1-m cable, BNC connector, 1 banana plug, NTC 30 kOhm
$195.00
YSI Hard Carrying Case
Hard-sided carrying case for the YSI 9500 Photometer
$210.00
$199.50
YSI Hard Carrying Case
Hard-sided carrying case for the YSI 9300 Photometer
$210.00
$199.50
YSI 200900Y Data Hub
900 series data hub for infrared data transfer
$225.00
$213.75
YSI 400355 TruLine ORP 50 Electrode
ORP electrode no temperature, single-junction, refillable, glass shaft with 1-m cable, BNC connector
$215.00
YSI 400364 ScienceLine Temp 136 Temperature Sensor
Temperature sensor, glass, 1 banana plug, NTC 30 kOhm
$230.00
YSI Pro1001A Amplified pH Sensor
Amplified pH sensor for the YSI Pro Series instruments
$230.00
YSI 400350 TruLine pH 15 Electrode
pH electrode with temperature, single-junction, 3 in 1, refillable, glass shaft with 1-m cable, BNC connector, 1 banana plug, NTC 30 kOhm
$235.00
YSI 400354 TruLine pH 27 Electrode
pH electrode no temperature, single-junction, combination, flat glass membrane, glass shaft w/1-m cable, BNC connector
$255.00
YSI 400363 ScienceLine Temp 135 Temperature Sensor
Temperature sensor, stainless steel, 1 banana plug, NTC 30 kOhm
$270.00
YSI 199163Y LSdata Software
LSdata software; GLP compliant PC software for data management and data transfer
$295.00
$280.25
YSI 400360 Science pHT-Pt Electrode
pH electrode with temperature, double-junction, Platinum junction, 3 in 1, glass shaft with 1-m cable
$300.00
YSI 6118 Rechargeable Battery Pack Kit
YSI 6118 Rechargeable Battery Pack Kit
$360.00
$342.00
YSI 400361 Science pHT-Pt Electrode
pH electrode with temperature, double-junction, 3 in 1, ground joint junction, glass shaft with 1-m cable
$350.00
YSI 400357 TruLine pH 21 Electrode
pH electrode no temperature, single-junction, combination, spear tip membrane, epoxy shaft with 1-m cable, BNC connector
$355.00
YSI 251301Y Lab Station
Lab Station for pHotoFlex series includes LSdata PC software, rechargeable batteries and univerisal plug, RS232. Barcode compatible
$379.00
$360.05
YSI 400362 Science pHT Electrode
pH electrode with temperature, double-junction, 3 in 1, Platinum junction, Micro electrode, glass shaft with 1-m cable
$475.00
YSI 400358 IoLine pH Electrode
pH electrode with temperature, triple-junction, Iodine/Iodide reference, 3 in 1, refillable, glass shaft with 1-m cable
$475.00
YSI 400359 IoLine Micro pH Electrode
pH electrode with temperature, triple-junction, Iodine/Iodide reference, 3 in 1, refillable, Micro electrode, glass shaft with 1-m cable
$610.00