HyQuest Solutions HyQual User manual

HyQual - Water Quality Multi-
Probe
HyQuest Solutions / KISTERS Group
2022-05-03

Table of Contents
1.1 Required Accessories/Options 5
2.1 General Safety Instructions 6
2.2 Specific Safety Instructions 7
4.1 Protection for unattended logging8
4.2 Operating limits 8
5.1 SNAPSHOT, AUTOSNAP, and LOGGING 8
5.1.1 Using Snapshot and Autosnap 9
5.1.2 LOGGING 9
5.2 Set Barometric Pressure 9
5.3Set Time and Date 10
6.1 Sensor Warm Up 10
6.2 Four Basic Deployment Methods10
6.2.1 Manual Data Collection 10
6.2.2 Unattended Logging 10
6.2.3 Telemetry Relay 11
6.2.4 On-Line Monitoring 12
7.1 When to proceed to maintenance? 12
7.2 Maintenance –1: Keep your device clean 12
7.3 Maintenance –1: Calibration 13
7.3.1 Basics of Parameter Calibration 13
7.3.2 Sensor Response Factor (SRF) 14
7.3.3 Choosing Calibration Standards 14
7.3.4 Calibration Record (Cal Log) 15
7.3.5 Temperature 15
7.3.6 Dissolved Oxygen 15
7.3.7 Conductivity 17
7.3.8 pH 17
7.3.9 Reference Electrode 18
7.3.10 ORP 18
7.3.11 Depth and Vented Depth 19
7.3.12 Turbidity 19
8.1 Use Status LED for Troubleshooting 20
8.2 Check active Components 21

8.2.1 Check if the Motherboard of the Sensor is OK 21
8.2.2 Check if any given sensor needs replacement 21
Descargo de responsabilidad
La información proporcionada en este manual se consideró precisa en la fecha de publica-
ción. Sin embargo, es posible que se hayan producido actualizaciones de esta información.
Este manual no incluye todos los detalles de diseño, producción o variación del equipo ni cu-
bre todas las situaciones posibles que puedan surgir durante la instalación, operación o man-
tenimiento. HyQuest Solutions no se responsabiliza de ningún daño incidental, indirecto, es-
pecial o consecuente que surja o esté relacionado con esta documentación y la información
contenida en ella, incluso si HyQuest Solutions ha sido advertida de la posibilidad de tales da-
ños.
Cualquier error encontrado en cualquier producto de HyQuest Solutions debe ser comuni-
cado a HyQuest Solutions, donde se hará todo lo posible para resolver rápidamente el pro-
blema.
Aviso de derechos de autor: Ninguna parte de esta obra puede ser reproducida en cualquier
forma o por cualquier medio sin el permiso escrito del editor. HyQuest Solutions renuncia a
los derechos de autor para que los usuarios puedan imprimir partes de la documentación en
papel para su propio uso.
Aviso de marca comercial: HyQuest Solutions (HS) y los productos y servicios de KISTERS a los
que se hace referencia en este documento son marcas comerciales o marcas registradas de
HyQuest Solutions o KISTERS AG. Otros nombres de productos utilizados pueden ser o no
marcas comerciales de sus respectivos propietarios.
2022 HyQuest Solutions, una empresa del Grupo KISTERS. Quedan reservados todos los dere-
chos no concedidos expresamente en este documento.

Glossary & Abbreviations
Term
Explanation
SDI-12
Serial Digital Interface at 1200 baud, an asynchronous serial communications protocol for
smart sensors, SDI-12 sensors reply to commands send by the data logger, the standard also
specifies supply voltage and current and including modes for low-power operation
USB
Universal Serial Bus, an asynchronous serial communication protocol for peripheral devices
EBP
External battery pack for HyQual 300 and HyQual 300 T
BP
Barometric Pressure
DO
Dissolved Oxygen
ODO
Optical Dissolved Oxygen
ORP
Oxidation-reduction potential
Redox
Reduction–oxidation, is a type of chemical reaction in which the oxidation states of sub-
strate change.
SC
Specific Conductivity
C
Conductivity
Modbus
Modbus is a serial communication protocol. Method used for transmitting information over
serial lines between electronic devices. There are two types of Modbus serial protocols, RS-
232 and RS-485. Modbus RS-232 allows concurrent, full-duplex flow of data. Modbus RS-
485 is half-duplex, and indicates values using differences in voltage. Modbus messages can
also be sent over Ethernet or TCP/IP.
RS 485
RS-485 is a serial interface, an industrial specification that defines the electrical interface
and physical layer for point-to-point communication of electrical devices. The RS-485 stand-
ard allows for long cabling distances in electrically noisy environments and can support mul-
tiple devices on the same bus. RS485 has a data transmission speed of up to 10Mb/s for a
distance of 15M. At the maximum of 1200M, RS485 transmits at 100Kb/s.
RS 232
RS232 is a serial communication which is more than able to perform for a short distance
and low data speed requirements. RS232 has a transmission speed of 1Mb/s up to 15M.
Recommended Standard 232 is a standard originally introduced in 1960 for serial communi-
cation transmission of data.
SNAP-
SHOT
Refers to manually capturing one line of readings, with the data stored in your Display
AU-
TOSNAP
Refers to automatically capturing data, with the data stored in your Display.
Logging
Refers to unattended data capture, with the data stored in The HyQual probe
Teleme-
try Re-
lay
It means that you have connected the HyQual probe to a telemetry device, deployed the
HyQual probe in the proper location in the water, and left the site.
SN
Serial number (the sensors have the SN of the probe)
RV
Raw voltage
SRF
Sensor response factor. Figure of merit for the calibration based on 100 as reference value.
Helps you know if calibration was properly done.

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Scope of Delivery
1x either HyQual 200 or HyQual 300 or HyQual 300T multi-probe
1x non-vented underwater cable (5, 10, 20, 30, 40 and 50 m)
Temperature sensor, dissolved oxygen sensor, specific conductivity sensor, pH sensor and ORP sensor
1x weighted sensor guard
1x kit: tool and maintenance
1x Internal memory
3-year warranty
Only for HyQual 300T: Turbidity sensor and its wiper
Interface RS-232
Soft carrying case
… and any option ordered with the multi-probe
1.1 Required Accessories
Power supply
HyQual probes require a source of power.
Choices of power supply out of the water:
⁻For spot measurements, the optional external rechargeable Bluetooth® wireless technology bat-
tery enclosed in a waterproof (IP67) case connects to the probe via the HyQual probe‘s standard
underwater cable running RS-232 or SDI-12. This battery operates only at the surface and its job
is to power the multiprobe while you’re pairing the instrument with a data display via
Bluetooth® wireless technology.
⁻A USB port on a PC is another way of suppling power to the multi-probes. For this case you
would need to add the optional USB adapter.
⁻HyQual also connects to third-party devices (data loggers, samplers, telemetry, etc.) that supply
power.
Choices of power supply that operate underwater:
⁻Instead of using power from the underwater cable you could use the optional EBP external re-
chargeable battery pack. This battery is ideal for HyQual 300 and 300 T due to its 75 mm (3 “)
diameter. It also works fine with the 200 version, only it makes it look top heavy. Use the EBP
external battery pack when you do not wish to have downtimes of charging the battery. The EPB
is removable so you can replace it with a freshly charged battery right in the field. Please note
that the use of EBP adds several millimeters to the length of the multiprobe.
Communication and connection
Available for the HyQual probes is an optional SDI-12 and ModBus interface, with either an SDI-12 or
MODBUS adapter cable.

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Connectivity and Visualization
When using a smartphone, tablet or other display device (Android™) you would need to add to your
package the Bluetooth® wireless technology battery pack which allows to connect the external device
with the probe via Bluetooth® wireless technology and additionally provides external power to the in-
strument.
HyQual also connects to a PC with the use of the optional USB Converter.
Vented capacity
With the vented depth sensor, the multiprobe automatically corrects depth measurments for changes in
Barometric Pressure.
Please note that vented capacity is optional, it requires to add an optional depth sensor, optional vented
depth capacity, and an optional vented cable.
Additionally, this capacity is incorporated in the probe so you will add it when purchasing the probe. If
you happen to have a probe and need to incorporate this capacity, you will have to send the probe back
to us at your own expense.
Additional sensors
Barometric pressure is calculated with the use of the depth sensor therefore, you will need to add an
optional depth sensor to any of your probes HyQual 200, HyQual 300 and HyQual 300T.
When Absolute Pressure method is used (non-vented capacity) there are three ways of obtaining the
value of Barometric Pressure:
a) With the use of a theorical Barometric Pressure
b) With the use of the depth sensor, by taking the probe out of the water and placing it at the water
surface so that the probe only measures the Barometric Pressure
c) With a barometer (any brand)
Please note that barometric pressure value is needed for the calibration of the DO sensor.
Safety Instructions
2.1 General Safety Instructions
Read the user manual including all operating instructions prior to installing, connecting and powering up
the HyQuest Solutions HyQual unit. The manual provides information on how to operate the product.
The manual is intended to be used by qualified personnel, i.e. personnel that have been adequately
trained, are sufficiently familiar with installation, mounting, wiring, powering up and operation of the
product.
Keep the user manual on hand for later reference.

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If you encounter problems understanding the information in the manual (or part thereof), please con-
sult the manufacturer or its appointed reseller for further support. HyQuest Solutions HyQual is in-
tended to be used in hydrometeorological or environmental monitoring applications.
Before starting to work, you have to check the functioning and integrity of the system.
Check for visible defects on the HyQual probe multi-probe, this may or may not include any or all of the
following: mounting facilities, connectors and connections, mechanical parts, internal or external com-
munication devices, power supplies or power supply lines, etc.
If defects are found that jeopardize the operational safety, work must be stopped. This applies for de-
fects found before starting to work as well as for defects found while working.
Do not use any HyQuest Solutions HyQual probe in areas where there is a danger of explosion.
The present user manual specifies environmental/climatic operating conditions as well as mechanical
and electrical conditions. Installation, wiring, powering up and operating any HyQuest Solutions HyQual
probe must strictly comply with these specifications.
Perform maintenance only when tools or machinery are not in operation.
If guards are removed to perform maintenance, replace them immediately after servicing.
Never make any electrical or mechanical diagnostics, inspections or repairs under any circumstances.
Return the sensor to the manufacturer’s named repair center. You can find information on how to re-
turn items for repair in the relevant section of the HyQuest Solutions website.
Disposal instructions: After taking any HyQuest Solutions HyQual probe out of service, it
must be disposed of in compliance with local waste and environmental regulations. Any
HyQuest Solutions HyQual probe is never to be disposed in household waste!
Inputs and outputs of the device are protected against electric discharges and surges (so-
called ESD). Please do not touch any part of the electronic components! If you need to
touch any part, please discharge yourself, i.e. by touching grounded metal parts.
2.2 Specific Safety Instructions
Handing of reagents needed for calibration purposes always requires special attention. Typically, the re-
agents used for calibration purposes of the multiprobe are considered to be non-hazardous.
Ensure that Safety Data Sheets (SDS) are available for all chemicals used.
In case of an incidents: consult these documents as they describe signs and symptoms of exposure, list
first-aid procedures, and spill cleanups.
Secure all chemicals: store them out of reach of unauthorized personnel, ensure safety during transpor-
tation and provide containers that will contain and resist the chemical in case of a spillage.
Label all chemical containers clearly.
Keep a handheld eyewash bottle in a chemical-safety kit at hand and close to the location where the
chemical reagents are used and stored.
If possible, use small dropper bottles or sample bottles prefilled with sufficient volume of preservative
instead of transporting large containers of preservatives. Handling smaller volumes of chemicals lowers
the risk and damage if a spill occurs.
Do not pipette by mouth. Always use mechanical pipettes or pipette bulbs.

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Introduction
HyQual is a precision analytical measurement instrument. It integrates several sensors to determine a
wide range of water quality parameters in a single housing. HyQual 200, HyQual 300 and HyQual 300T
are individual complete solutions and depending on the chosen model and optional extensions, the
multi-probes can determine a subset or all of the following parameters:
Temperature (standard), dissolved oxygen (standard), specific conductivity (standard), pH/ORP (stand-
ard), total dissolved solids (standard), salinity (standard) and turbidity (standard and only possible in
HyQual 300T), depth/level (optional) and barometric pressure (optional).
Installation
The probes should be installed in a place where there is a sufficient water flow, that can be easily ac-
cessed for maintenance and protected from external elements such as animals and items such as stones
or sticks that may damage the probe.
4.1 Protection for unattended logging
There are 4 pipe kits available:
▪Pipe kit 2 ‘’ diameter: For protecting multiprobes, hinged locking cap
▪Pipe kit 4’’ diameter: For protecting multiprobes, hinged locking cap
4.2 Operating limits
▪Input voltage: 5 VDC to 15 VDC
▪Storage temperature: 1 C to 50 C
▪Max. depth:
▪50 m
▪10 m for ISE or TDG
Configuration
5.1 SNAPSHOT, AUTOSNAP, and LOGGING
“Logging” refers to unattended data capture, with the data stored in The HyQual probe. The data are
tagged with time and date. Logging is useful if the HyQual probe needs to collect data for days or weeks
at a remote location.
“Snapshot” refers to manually capturing one line of readings, with the data stored in your Display. If
you wish to log specific readings, tap the Snapshot button to save that data in your Display. The data
will be tagged with time and date, and you can add an annotation if you wish.

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“AutoSnap” refers to automatically capturing data, with the data stored in your Display. If you are run-
ning a short-term experiment or are monitoring site for a few hours, AutoSnap will take a series of snap-
shots at the same interval as that you set for the interval between lines of rolling data.
5.1.1 Using Snapshot and AutoSnap
All of the user-interface versions have Hot Buttons for Snapshot and AutoSnap on the Home Screen.
Simply press the button for the feature you wish.
You can change the file name you’re using for Snapshots and AutoSnap (they’re in the same file) any
time you wish.
5.1.2 LOGGING
5.1.2.1 Setting the Logging Interval
Go to the Logging section of your user-interface and follow the menu to set the Logging interval.
5.1.2.2 Activating Logging
To initiate Logging, you must tell the HyQual probe that you want it to start logging. All of the user-in-
terface versions have a Hot Button for turning Logging on, or off, on the Home Screen. Simply press the
button to toggle between Logging ON and Logging OFF.
The Setup function for Logging lets you name your Logging file, and set the logging interval (time be-
tween logged lines of data).
Figure 1 –Switch Logging ON or OFF
Once Logging is ON, supply the HyQual probe with power to start Logging. For convenience, you may
wish to take a Display to the field so that you can activate Logging right before you place the HyQual
probe in the water.
Please be aware that the blinking green LED communicates that you have adequate voltage to begin log-
ging, and the blinking red LED (once you power up) that Logging is properly enabled.
5.2 Set Barometric Pressure
The HyQual probe needs to have information about the local Barometric Pressure (BP) when calibrating
DO. To calibrate BP, open the Calibration menu, select “Set BP”, and type in the correct value (in mm
Hg) in the first box on the screen.
If you do not have information about the BP, you can set the approximate BP by typing your altitude (in
feet) in the second box. Please notice that if you type in BP, altitude is automatically calculated, and
vice-versa. The third method for setting BP is asking the HyQual probe the value (if the HyQual probe is
equipped with a non-vented Depth sensor). If you choose this method, the correct values will automati-
cally appear in the BP and altitude boxes.

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5.3 Set Time and Date
To calibrate Time and Date, open the Calibration menu, select “Set Time and Date” to see the HyQual
probe’s current time and date. If you wish to change any of those values, just type the new value in the
appropriate box or click the box at the bottom of the screen. If you wish to synchronize the HyQual
probe time and date with that of your Display, click the “synchronize” box.
Operation
6.1 Sensor Warm Up
The HyQual probe knows the warm-up times required for all the sensors you have enabled. It figures
out exactly when to turn the various sensors on so that a frame of data can be taken exactly at the cor-
rect time. For instance, the DO sensor takes 20 seconds to warm up and the turbidity sensor takes 25
seconds to warm up. So, if you have only a DO sensor, the warm-up time will be 20 seconds. If you
have DO and turbidity sensors, the warm-up time will be 25 seconds.
6.2 Four Basic Deployment Methods
There are four basic deployment methods for The HyQual probe.
6.2.1 Manual Data Collection
Manual Collection is also known as profiling, surveying, spot measurement, site-to-site measurements,
etc., means you are present at the monitoring site and using a Display for observing measurements.
This allows you to make data-based decisions in the field in real-time at multiple monitoring sites in one
day. The Display can be a laptop, or almost any tablet or smart phone. You can record measurements
using the HyQual probe’s Snapshot or Automatic Snapshot features. You might “snapshot” a series of
measurements in one or more lakes or streams during the day, and then download your data to your
desktop PC that evening. If your Display has email, you can email the data to anyone you wish, including
yourself.
6.2.1.1 Uploading Snapshot and AutoSnap Data
If you are using a phone or tablet as your display, Snapshot and AutoSnap data are stored in your Dis-
play. If you wish to upload that data to a PC, simply follow the same procedure you would use to syn-
chronize your PC and phone or tablet to transfer pictures, contact lists, etc.
You can also email data files from your phone or tablet if they have Web access.
6.2.2 Unattended Logging
Unattended Logging means that you have set the HyQual probe into its Logging mode, deployed the
HyQual probe in the proper location in the water, and left the site. The HyQual probe can run for weeks
at a time with cable-supplied power or an optional HyQual Internal Lithium Battery Pack. You can, for
instance, set the instrument to take a set of readings every half-hour, anchor it in an estuary, and return
after two weeks to retrieve the instrument and download the data to a PC, laptop, tablet, or phone.
6.2.2.1 Log Start on Power Up
HyQual starts logging when the user activates logging (see 5.1), and then provides power.
When power is first provided, the red LED will blink five times to confirm that Logging is activated, and
the green LED will blink briefly to confirm that the HyQual probe is receiving adequate voltage to start
Logging.

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6.2.2.2 HyQual Logging: time uniformity.
For instance, if your logging interval is 15 minutes and you turn Logging on at five minutes past 10 AM,
your first data will be logged at exactly 10:15, and then every 15 minutes thereafter. If your logging in-
terval is one hour and you turn Logging on at five minutes past 10 AM, your first data will be logged ex-
actly at exactly 11 AM, and then every hour thereafter. Your data is cleaner, and it’s easier to match
times if you wish to merge data sets.
6.2.2.3 Managing Log Files and Uploading Logging Data
Go to the Logging section of your user-interface and follow the menu to name Logging files, change Log-
ging files, erase Logging files, or upload Logging Data to a PC.
6.2.2.4 Powering the HyQual probe in Logging Mode
You can log data using an External Battery Pack (EBP) which is plugged to the probe or power from a
secondary power source (such as a solar-recharged storage battery located above the water surface) via
the Underwater Cable.
If you have an EBP and a secondary power source attached, the HyQual probe will use power coming
from the secondary power source if its voltage is sufficient. If the HyQual probe cannot find adequate
voltage in the Underwater Cable, it will use its EBP. This process preserves The HyQual probe batteries
when possible. Other manufacturers, for reasons unknown, use the power source with the highest volt-
age, meaning that their batteries may be consumed quickly.
The HyQual 300 and HyQual 300 T probes can be ordered with an optional External Battery Pack (EBP), a
lithium rechargeable battery that you fix to the probe by plugging it, this means that you can purchase
this battery after as it is not integrated to the probe. Please note that this battery ads several inches to
the length of the probe and that it can also be used with the HyQual 200 only that its diameter would be
larger than the HyQual 200’s diameter which will make the probe look top heavy but it will work
properly.
With an EBP, Logging starts when you use the Hot Button on the Home Screen to toggle from Logging
OFF to Logging ON.
The EBP is a rechargeable, “smart” Lithium battery that operates underwater and it avoids downtime for
charging the battery as you can replace it in the field with freshly recharged batteries without having to
take the probe out of water.
The EBP will power the HyQual probe for roughly 40 days with a logging interval of 15 minutes in 25C
water.
6.2.3 Telemetry Relay
Telemetry Relay means that you have connected the HyQual probe to a telemetry device, deployed the
HyQual probe in the proper location in the water, and left the site. An Underwater Cable connects the
HyQual probe to the telemetry system. The telemetry device uses satellite or cell-phone communica-
tion to periodically report HyQual data to your office PC or to a proprietary Web page. In many teleme-
try systems, you can also contact the HyQual probe and request transmission of the most recent data.
Telemetry Relay lets you collect data all night and all day for weeks without being present at the moni-
toring site and allows you remote access to collected data at any time. Telemetry is helpful in optimiz-
ing trips to the field for HyQual calibration or maintenance. Telemetry is also ideal in locations for which
access is dangerous or expensive.
6.2.3.1 Logging Redundantly with Telemetry
If you wish to add redundancy to your data collection, you can connect a HyQual to a third-party data
logger, telemetry device, etc. to store data in the HyQual probe (using its standard Logging function)
and in the third-party device (according to its manufacturer’s instructions).

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If you will be using an Underwater Cable, you can run power to the HyQual probe from a surface power
supply to provide power to HyQual –you don’t need a HyQual Battery Pack.
Or, the surface power supply can power HyQual with the optional internal lithium battery pack, thus
saving your batteries for emergencies such as the failure of the surface power supply.
Either way, you will end up with data records in both the HyQual probe and the third-party device.
6.2.4 On-Line Monitoring
On-Line Monitoring, also known as process-control monitoring, means that the HyQual probe is con-
nected to a PLC, SCADA system, etc. An example is monitoring the input to a water-treatment plant for
salinity or chlorophyll. On-Line Monitoring allows you to make water-quality-based decisions in real-
time. The HyQual probe is particularly effective in this application when more than one parameter is
needed in the control loop or decision-making process.
Maintenance
7.1 When to proceed to maintenance?
Judgment gained from observing your field conditions and data requirements provides information
about when to maintain sensors. If you are logging data over long periods, the time when you collect
your data from the HyQual probe is a good time for maintenance and calibration.
7.2 Maintenance –1: Keep your device clean
Clean your instrument periodically with warm soapy water - liquid dishwashing soap is fine. Do not use
abrasives or strong solvents (such as acetone). Do not clean with gasoline, kerosene, or industrial clean-
ers. Mild household cleaners work well. You can clean sensor stems with a soft brush, but use only a rag
or paper towel when cleaning the sensor’s actual measurement surface.
Figure 2 –Rinsing a HyQual multiprobe
Rinse the HyQual probe well with tap water after cleaning, and store sensors with a few ounces of tap
water in the Storage/Calibration Cup.
If you take the HyQual probe apart and expose O-rings, keep them, and their mating surfaces, greased
with silicon grease (found in your Maintenance Kit). The same applies to your Underwater or Data Ca-
ble’s lower connector. Replace any O-rings with visible cracks.

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Figure 3 –Getting access to O-Rings
Always remove batteries (if any) and clean The HyQual probe prior to storing it for prolonged periods.
Always refill the reference electrode and recalibrate after long storage periods.
7.3 Maintenance –1: Calibration
7.3.1 Basics of Parameter Calibration
The procedure for operating a HyQual, including making calibrations, varies with the type of Display
used because the user-interface software can be different (mostly because of the differences in Display
screen sizes). You could also study the highly detailed Appendices to familiarize yourself with the vari-
ous procedures. Otherwise, you should be able to walk through the software once you have established
communication between your Display and the HyQual probe. You can become a minor expert in just a
few minutes.
The HyQual probe never guesses parameter values, so you must calibrate it from time to time by simply
telling the instrument what it should read in a calibration situation for which the correct parameter
value is known. Here’s the general procedure:
1. Clean the sensor and perform any necessary sensor-specific maintenance.
2. Select a calibration standard whose value is close to the values you expect to see in the field.
For best results, use fresh calibration solutions, and discard them once they have been used.
But generally, you can reuse most calibration standards a few times if you are careful to avoid
contamination.
3. With the HyQual probe’s Storage/Calibration Cup screwed onto the HyQual probe housing, rinse
the sensors three times with a small quantity of your calibration standard by pouring the stand-
ard into the Storage/Calibration Cup, positioning the “stopper” side of the lid (the side with the
O-ring) on top of the Storage/Calibration Cup, and shaking the HyQual probe vigorously to re-
move traces of old calibration solutions. Discard the used calibration standard between rinses.
4. Next secure The HyQual probe with the sensors pointing up and fill the calibration cup with your
calibration standard. Make sure the standard covers the sensor entirely, and that it also covers
the thermistor for those parameters that are temperature-compensated. For turbidity sensors
and other fluorometers fill the cup to at least 1 ½ inches above the sensor’s lens surface.

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5. Access your app’s calibration function by navigating from the Home Screen to the calibration
section. Select the parameter to be calibrated, and then enter the calibration value in the type-
in box, and press enter. When the reading has stabilized, press enter to calibrate. The HyQual
probe will report the resulting Sensor Response Factor (SRF; see below). For most apps, you
then press Y to accept the calibration, N to back up one step, or Exit to leave the sensor uncali-
brated.
7.3.2 Sensor Response Factor (SRF)
Near the end of the calibration routine, you will be asked to
accept or decline the calibration based on the Sensor Re-
sponse Factor (SRF). Suppose that a “typical” Conductivity
sensor puts out 100 μA in a 1413 μS/cm standard. If your
Conductivity sensor reports 100 μA in that same calibration solution, then your SRF is 100% (some pa-
rameters, such as pH, have a more complex SRF calculation, but the effect is the same). If your response
is 80 μA, your SRF would be 80%. When you press the OK button to accept a calibration, the HyQual
probe automatically accepts your calibration if the SRF is between 60% and 140%. If the SRF falls out-
side that range, you will be cautioned to check your standard value, make sure the sensor is clean, make
sure the reading has stabilized, etc. But you can elect to accept any SRF.
7.3.3 Choosing Calibration Standards
For best results, choose a calibration standard whose value is close to what you expect to see in the
field. For example, calibrate with a 1413 μS/cm Specific Conductance standard if you expect to see Spe-
cific Conductance readings between 500 and 1000 μS/cm in the field. Calibrating with a sea water stand-
ard or a very low standard would not be appropriate. Similarly, if your waters tend toward the acidic,
calibrate with a 4-buffer instead of a 10-buffer.
If you are moving The HyQual probe across wide ranges of water conditions, you may wish to recalibrate
to match the new situations. For instance, if you are measuring a clear lake during the morning and a
high-sediment stream in the afternoon, you might consider recalibrating at noon with a high-value tur-
bidity standard.
The table below shows common calibration practices.
Table 1 –Common Calibration Practices
Sensor
Standard Method of Calibration
Available Calibration Solutions
Comments
Temperature
never requires calibrating
N/A
pH / pH reference
2 or 3 points
pH 4, pH 7, pH 10
pH7, pH 10 most common
ORP
1 point
ORP Standard 200 mV
Conductivity
1 point
CD Standard, 0.5 Molar, 58670 Micro S
CD Standard, 0.1 Molar, 12856 Micro S
CD Standard, 0.01 Molar, 1412 Micro S
CD Standard, 0.001 Molar,147 Micro S
brackish/saltwater
borderline brackish typical
freshwater very pure
fresh/glacial
Reference Electrode
calibration not required
N/A
replace pH electrolyte
solution at routine
calibration
Depth
adjust for barometric pressure
N/A
recalibrate at deployment
site for best accuracy

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Turbidity
2 points
0 NTU, 10 NTU, 100 NTU, 400 NTU
calibrate near expected
value
HDO (Optical DO)
calibrate at 100% saturated
water
DI water -shake vigorously to
oxygenate
set BP before calibrating,
recal at deployment site
for best accuracy
Chlorophyll
2 points
secondary solid or 40µg/L solution
or lab sample
Rhodamine
2 points
secondary solid standard or
rhodamine
Blue Green Algae
2 points
secondary solid standard or lab
sample
Ammonium (NH4+)
2 points
Lo 4.63 mg/l; Hi 46.3 mg/l
Nitrate (NO3+)
2 points
Lo 4.62 mg/l; Hi 46.2 mg/l
Chloride (CL-)
2 points
CD Standard 147 Micro S
CD Standard 1412 Micro S
enter 34.3 mg/l for low cal
enter 319.3 mg/l for high cal
7.3.4 Calibration Record (Cal Log)
Every HyQual probe has a dedicated data file called CAL.LOG. The CAL.LOG records every calibration
made to your instrument, whether you accepted the calibration or not. This file shows the time and date
of the calibration, the parameter calibrated, the reading before the calibration was accepted, the read-
ing after the calibration was accepted, the “raw” sensor reading, the SRF, and a few other details. If you
wish to know, for instance, the last time that DO was calibrated, the Calibration Record would tell you
when the most recent DO calibration was made, the value of the calibration standard, and the instru-
ment’s reading in the standard before the calibration was made (to tell you exactly how much the in-
strument was changed during calibration). Please notice that this data cannot be altered within the
HyQual probe!.
7.3.5 Temperature
The Temperature sensor is an electrical resistor (thermistor) whose resistance changes predictably with
temperature. The sensor is protected by a stainless-steel tube. Thermistors are very stable with time, so
are factory-calibrated and do not require recalibration.
7.3.6 Dissolved Oxygen
The optical dissolved-oxygen sensor is a blue-light source, a sensing surface, and a red-light receiver.
The sensing surface is an oxygen-active compound stabilized in an oxygen-permeable polymer, usually
silicone. When the sensing surface is exposed to oxygen (in water or air), oxygen diffuses into the sens-

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ing surface according to the amount (partial pressure) of oxygen in the sample. The oxygen-active com-
pound fluoresces by absorbing energy in the form of blue light and then emitting energy as red light.
Oxygen “quenches” that fluorescence, so the more oxygen, the less fluorescence.
In each measurement cycle, the blue light is first turned on, and then turned off. The red-light receiver
measures the time it takes, after the blue light is turned off, for the fluorescence to die off. This value is
proportional to dissolved oxygen.
DO readings are corrected for the water sample’s temperature and salinity (if you have a Conductivity
sensor).
HyQuest Solutions recommends the “air-saturated water” DO calibration method, as opposed to the
“water-saturated air” calibration commonly used in the past. Here are the steps to air-saturated water
calibration:
1. Make sure your instrument’s Barometric Pressure setting is accurate. (C.14)
2. Open the Calibration menu and select “ADO %sat” for HyQual
3. Put a half-liter of tap water in a liter jar, secure the lid, and shake the jar vigorously for one mi-
nute. Take the lid off the jar and let the water stand for about five minutes so air bubbles float
out.
4. Screw your calibration cup onto the HyQual probe housing and remove the cup lid. With the
sensors pointed upward, fill the calibration cup until your aerated water covers the DO sensor
by a centimeter or so.
5. Wait a few minutes for the temperature to equilibrate and the sensor to arrive at a steady read-
ing.
6. Now just follow the calibration instructions on the screen.
The manufacturers of optical-DO sensors usually recommend that you not calibrate the zero-DO point
because the zero-DO point drift is very low. However, The HyQual probe supports zero-DO calibration,
should you wish to check your sensor’s zero from time to time, using any of three methods:
1. Dissolve a few grams of sodium sulfite and a pinch of cobalt chloride in a half-liter of tap water.
You can buy this solution ready-to-use but be careful not to aerate the solution by pouring it
back and forth numerous times.
2. If you do not wish to use the sodium-sulfite method , you can prepare zero-oxygen water by
bubbling nitrogen through water. Use bottled gas and an aquarium-type air stone. (If you’re
using a high-pressure gas bottle, please use a two-stage regulator to prevent unnecessary ex-
citement.) After bubbling the gas through, say, a liter of water for, say, 10 minutes, you should
have a good zero.
3. The simplest way to check zero response is with nitrogen gas. Wrap the sensor-end of The
HyQual probe with a plastic bag, and feed nitrogen gas into the bag. Make sure there’s another
hole at the opposite end of the bag for the air to escape, otherwise you won’t get a good zero
and the exploding bag will cause unnecessary excitement. (If you’re using a high-pressure gas
bottle, please use a two-stage regulator.)
Optical dissolved-oxygen sensor maintenance is little more than occasionally cleaning the sensing sur-
face (the dark material, about a centimeter diameter, at the tip of the sensor) with a cloth and soapy
water.
Optical dissolved-oxygen sensors usually have very low drift rates . Practice will show you how often to
calibrate DO, and you might find that one or the other of the calibration points (zero or 100% satura-
tion) does not require calibration every time you set the other point.

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7.3.7 Conductivity
HyQuest Solutions uses the four-electrode method to determine water conductivity. Two pairs of
graphite electrodes are situated in a stable geometry (you can barely see the electrodes; they look like
two bull’s eyes inside the slot on the conductivity sensor).
A constant voltage is applied to one of each electrode pair, and the amount of current required to main-
tain that voltage is measured. As the conductivity of the water increases, the current increases predicta-
bly.
Conductivity sensor maintenance is nothing more than occasionally cleaning the measurement surface
with a soft cloth or cotton swab and soapy water. Do not use anything abrasive.
The zero point for the sensor is set electronically, so you need only set the “slope” point:
1. Open the Calibration menu and select “SpCond µS/cm” or “SpCond mS/cm”, depending on your
preference of units.
2. Screw your calibration cup onto the HyQual probe housing and remove the cup lid. Rinse your
sensors several times with the standard you’ll use for calibration.
3. With the sensors pointed upward, fill the calibration cup until your solution covers the sensors
by an inch or so.
4. Wait a few minutes for the temperature to equilibrate and the sensor to arrive at a steady read-
ing.
5. Now just follow the calibration instructions on the screen.
The HyQual probe normally reports Specific Conductance –that’s Conductivity that has been standard-
ized to 25°C. Your reading is thus the conductivity of your water if that water was exactly 25°C. Conduc-
tivity has three other forms, Total Dissolved Solids (TDS), Salinity, and Resistivity (which we don’t report
because it has little meaning in natural waters). You can’t calibrate TDS or salinity directly because they
are calculated from Conductivity. You can, however, “calibrate” TDS with a TDS standard by adjusting
the conductivity calibration point up or down until the TDS standard produces the desired TDS reading.
The same is true for Salinity if you’re using a standard quantified on the Practical Salinity Scale (PSS).
"Enable" TDS and/or Salinity by checking the box next to those parameters in the "Sensors and Parame-
ters" section.
7.3.8 pH
pH is measured as the voltage drop across the glass membrane of a pH electrode. A reference electrode
is used to complete the voltage-measuring circuit. The pH glass is specially formulated to absorb water
so that ions (particularly H+ and OH-) in the water are attracted to the glass to offset the ionic constitu-
ency of the pH electrode’s internal electrolyte. As a result, there is a charge separation across the glass,
and that’s the voltage we measure. pH readings are automatically compensated for temperature.
pH electrode maintenance is nothing more than occasionally cleaning the glass surface with a soft cloth
and soapy water. Do not use anything abrasive. The important part of pH maintenance is refilling the
reference electrode. (D.10)
You can choose a two- or three-point pH calibration. The two-point calibration, a seven buffer and a
second buffer whose value is near that of the waters you intend to monitor, is recommended. If you are
measuring in waters whose pH might range significantly above and below seven, you may be able to in-
crease your accuracy slightly by choosing a three-point calibration (seven buffers plus one basic buffer
and one acidic buffer). pH calibration is simple:
1. Open the Calibration menu and select “pH”.
2. Screw your calibration cup onto the HyQual probe housing and remove the cup lid. Rinse your
sensors several times with the standard you’ll use for calibration.

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3. With the sensors pointed upward, fill the calibration cup until your solution covers the sensors
by an inch or so.
4. Wait a few minutes for the temperature to equilibrate and the sensor to arrive at a steady read-
ing.
5. Now just follow the calibration instructions on the screen.
6. Repeat steps 2 –5, as directed by the software, if you wish to calibrate at a second or third pH
value.
7.3.9 Reference Electrode
The key to reliable pH, ORP, and ISE measurements is a well-maintained reference electrode. Recall that
a reference electrode is required to complete voltage measurement for pH readings.
Reference electrode maintenance is simple:
1. Remove the reference cap by unscrewing it from the reference sleeve and discard old reference
electrolyte.
2. Fill the sleeve completely with fresh pH reference electrolyte (KCl saturated with silver chloride).
Tap the HyQual probe a few times to dislodge any bubbles.
3. Screw the reference cap back on to the sleeve. As you screw the sleeve into place, air and ex-
cess electrolyte is forced out of the sleeve through the reference electrode junction (the white,
porous circle at the end of the sleeve). This not only purges bubbles from the electrolyte, but
also cleans nasty stuff out of the junction.
Figure 4 –Filling in fresh pH reference electrolyte
7.3.10 ORP
ORP is also known as Oxidation-Reduction Potential or Redox. The actual ORP sensor is the 1 mm plati-
num dot you can see when looking down at the pH sensor –if The HyQual probe has ORP. Because plat-
inum does not react with ions in the water, it won’t give or take any electrons from those ions unless
they are very persuasive. The potential (voltage) created by this refusal is what you’re actually measur-
ing as ORP. As it is with pH measurement, the reference electrode completes the voltage-measuring cir-
cuit.
ORP electrode maintenance is nothing more than occasionally cleaning the platinum surface with a soft
swab and soapy water. If the platinum is discoloured, you can polish the ORP electrode with very light
abrasive, like 900-grit wet-and-dry sandpaper (please be careful not to polish the pH glass bulb). The
important part of ORP maintenance is refilling the reference electrode. (D.9)
ORP uses a one-point calibration:
1. Open the Calibration menu and select “ORP”.
2. Screw your calibration cup onto the HyQual probe housing and remove the cup lid. Rinse your
sensors several times with the standard you’ll use for calibration.
3. With the sensors pointed upward, fill the calibration cup until your solution covers the sensors
by an inch or so.

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4. Wait a few minutes for the temperature to equilibrate and the sensor to arrive at a steady read-
ing.
5. Follow the calibration instructions on the screen.
7.3.11 Depth and Vented Depth
Depth is measured by a strain-gauge transducer as hydrostatic water pressure. The deeper you go in
the water, the higher the pressure.
HyQuest Solutions’ Depth sensors are usually buried inside the instrument, with a small pressure port
that can be seen on the outside of the HyQual probe bottom cap. They require no regular maintenance,
but you might check occasionally to make sure the pressure port is not clogged. If it is, use something
soft, like a toothpick, to clear the port of obstruction.
Depth calibration is nothing more than “zeroing” the sensor in air, where one assumes the water depth
to be zero:
1. Make sure the HyQual probe is not in the water.
2. Open the Calibration menu and select “Depth”.
3. Now just follow the calibration instructions on the screen.
Please notice that the Depth sensor cannot distinguish between water pressure and the air pressure
over that water (i.e., barometric pressure). After you have zeroed the sensor, any change in barometric
pressure will be measured as a change in water pressure.
Another choice is using Vented Depth (Stage). Vented Depth uses the same transducer as does Depth,
except that there’s a small hole in the back of the transducer. There is a tube inside the cable (i.e., a
Vented Cable) to connect the Stage sensor to the atmosphere so that changes in barometric pressure
will not affect the Depth reading.
Vented-Depth cables have a desiccant-filled housing at their surface end. The desiccant keeps water
from condensing in the vent tube by letting vapor escape through a small Gortex patch. Keep that hous-
ing clean and replace the desiccants every year.
7.3.12 Turbidity
Turbidity is measured as the fraction of an infrared light beam that is scattered at 90° to that beam.
More particles in the water mean more of that light is scattered, so the Turbidity reading is higher.
Any material that accumulates on the optical surfaces of the Turbidity sensor is indistinguishable from
material in the water, so most Turbidity sensors have little wipers to clean the window(s).
Turbidity sensors require no regular maintenance, but you might check occasionally to make sure the
optical window (i.e. the little glass port on the front of the sensor) has not been damaged by overzeal-
ous wiping.
Turbidity uses a two-point calibration; one point is zero turbidity and the other point should be a stand-
ard approximating the turbidity of the water you intend to monitor.
Make sure you use enough calibration standard to cover the sensor’s “optical volume” – imagine a golf
ball stuck on the end of the sensor; make sure there are no objects in the volume represented by that
ball. One common method is keeping calibration solutions in one-litre, dark, wide-neck bottles with a
non-reflective finish (such as Nalgene 2106 bottles in amber).
For the zero calibration:

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1. Open the Calibration menu and select “Turb NTU” of “Turb FNU” depending on your preference
for measurement units.
2. Screw your calibration cup onto the HyQual probe housing and remove the cup lid. Rinse your
sensors several times with the standard you’ll use for calibration.
3. With the sensors pointed upward, fill the calibration cup until your solution covers the sensors
by at least an inch or so.
4. Wait a few minutes for the temperature to equilibrate and the sensor to arrive at a steady read-
ing.
5. Follow the calibration instructions on the screen.
If you wish to calibrate at a second point, repeat steps 2 –5 with a different turbidity standard.
A clean wiper means better measurements. If the wiper pad has deteriorated or is clogged with debris
from your water (algae, silt, etc.), you should change it. For best results, you might consider changing
the wiper pad prior to each long-term deployment. To change the wiper pad:
1. Make sure you have the 1.5mm hex key and a new pad for the wiper. Loosen the small set
screw on the wiper arm.
2. Remove the wiper pad from the wiper arm and replace the pad.
3. Place a new wiper arm on the motor shaft so that the set screw faces the flat spot on the motor
shaft.
4. Gently press the wiper pad against the face of the probe until the pad is compressed to roughly
three quarters of its original thickness. It is important that the wiper arm does not contact the
probe face –only the pad should be in contact. A gap of 0.5 mm between the wiper arm and
the probe face is typical when a new pad has been installed. Another way of setting the pad gap
is to place the pad such that you can slide a small piece of paper under the pad, but snug
enough that the pad will hold the paper.
5. Tighten the set screw.
Do not over-tighten the set screw on the little rotating arm that holds the wiper pad as that will strip the
threads. Do not rotate the wiper arm manually either as that will strip the gears.
Troubleshooting
We designed the HyQual probes so you do not be a specialized technician troubleshooting if something
goes wrong.
8.1 Use Status LED for Troubleshooting
Any HyQual probe has three light-emitting diodes (LED’s) mounted on the circuit board and visible
through the instrument housing, to help you understand what the HyQual probe is doing or not doing,
and to provide information when troubleshooting.