• Go Direct Salinity
• Micro USB Cable

Choose a platform below to see its compatibility requirements.

LabQuest

Interface	LabQuest App
LabQuest 3	Full support
LabQuest 2	Full support 1
LabQuest	Incompatible

Compatibility Notes

1. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

Computers

	Software
Interface	Graphical Analysis
No interface required	Full support 1
LabQuest 3	Full support 2
LabQuest 2	Full support 2 3

Compatibility Notes

1. For Bluetooth^® connectivity, only computers running Windows 10 or Mac OS X 10.10 or newer are supported. The computer must also have a compatible Bluetooth 4.0⁺ radio.
2. Connect this sensor directly to a computer or Chromebook via a USB or wireless Bluetooth^® connection for best results. Alternatively, this sensor is fully supported when used with LabQuest 2 or LabQuest 3 when the LabQuest is connected to a computer or Chromebook via Wireless Data Sharing.
3. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

Chromebook

	Software
Interface	Graphical Analysis
No interface required	Full support
LabQuest 3	Full support 1
LabQuest 2	Full support 1 2

Compatibility Notes

1. Connect this sensor directly to a computer or Chromebook via a USB or wireless Bluetooth^® connection for best results. Alternatively, this sensor is fully supported when used with LabQuest 2 or LabQuest 3 when the LabQuest is connected to a computer or Chromebook via Wireless Data Sharing.
2. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

iOS

	Software
Interface	Graphical Analysis	Graphical Analysis GW
No interface required	Full support	Incompatible
LabQuest 3	Full support 1 2	Full support 1 2
LabQuest 2	Full support 1 2 3	Full support 1 2 3

Compatibility Notes

1. Connect this sensor directly to a supported mobile device via a wireless Bluetooth^® connection for best results.
2. iOS and Android^™ devices can only connect to LabQuest 2 or LabQuest 3 via Wireless Data Sharing.
3. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

Android

	Software
Interface	Graphical Analysis	Graphical Analysis GW
No interface required	Full support	Incompatible
LabQuest 3	Full support 1 2	Full support 1
LabQuest 2	Full support 1 2 3	Full support 1 3

Compatibility Notes

1. iOS and Android^™ devices can only connect to LabQuest 2 or LabQuest 3 via Wireless Data Sharing.
2. Connect this sensor directly to a supported mobile device via a wireless Bluetooth^® connection for best results.
3. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

Python

	Software
Interface	Python
No interface required	Full support

Javascript

	Software
Interface	Javascript
No interface required	Full support 1

Compatibility Notes

1. A wireless Bluetooth^® connection can be made with Go Direct sensors on any platform running a browser with WebBluetooth support. However, only a few operating systems have been tested and testing has been limited.

LabVIEW

	Software
Interface	NI LabVIEW
No interface required	Full support 1

Compatibility Notes

1. For Bluetooth^® connectivity, only computers running Windows 10 or Mac OS X 10.10 or newer are supported. The computer must also have a compatible Bluetooth 4.0⁺ radio.

Connect Go Direct Salinity to the included Micro USB Cable and any USB device for two hours.

You can also charge up to eight Go Direct Salinity Sensors using our Go Direct Charge Station, sold separately (order code: GDX-CRG). An LED on each
Go Direct Salinity indicates charging status.

Charging	Blue LED on steady while sensor is connected to the Charging Cable or Charge Station.
Fully charged	Blue LED is off when charging is complete.

Turning on the sensor	Press button once. Red LED indicator flashes when unit is on.
Putting the sensor in sleep mode	Press and hold button for more than three seconds to put into sleep mode. Red LED indicator stops flashing when sleeping.

See the following link for up-to-date connection information:

www.vernier.com/start/gdx-sal

Connecting via Bluetooth

Ready to connect	Red LED flashes when sensor is awake and ready to connect via Bluetooth.
Connected	Green LED flashes when sensor is connected via Bluetooth.

Connecting via USB

Connected and charging	Blue and Green LED solid when sensor is connected to Graphical Analysis via USB and unit is charging. (Green LED is obscured by the blue one.)
Connected, fully charged	Green LED solid when sensor is connected to Graphical Analysis via USB and the unit is fully charged.
Charging via USB, connected via Bluetooth	Blue LED is solid and green LED is flashing, but the green flashing LED looks white because it is overwhelmed by the blue.

When two or more sensors are connected, the sensors can be identified by tapping or clicking Identify in Sensor Information.

Taking Measurements with Go Direct Salinity

• Rinse the tip of Go Direct Salinity with distilled water. Blot the inside of the electrode cell dry to avoid water droplets diluting or contaminating the sample to be tested.
• Insert the tip of the sensor into the sample to be tested. Important: Be sure the electrode surfaces in the elongated cell are completely submerged in the liquid and that there are no bubbles around the electrode surface.
• While gently swirling the probe, wait for the reading on your data-collection device to stabilize.
• Rinse the end of the probe with distilled water before taking another measurement.
• Important: The sensor should be stored clean and dry. It can be submerged in water for limited periods of time. It has been tested to a depth of one meter for up to 30 minutes. If the entire sensor, including the USB port, has been submerged in salt water, dunk the entire sensor in DI water for rinsing before storage.
• Important: Do not place the electrode in viscous, organic liquids, such as heavy oils, glycerin (glycerol), or ethylene glycol. Do not place the probe in acetone or non-polar solvents, such as pentane or hexane.

Channels

Go Direct Salinity has three measurement channels:

• Salinity
• Salinity zero percent (non-temperature compensated conductivity)
• Temperature

Using the Salinity Sensor with Other Vernier Sensors

Some combinations of sensors interfere with each other when placed in the same solution. The degree of interference depends on many factors, such as the combination of sensors being used and the interface to which the sensors are connected. For more information, see www.vernier.com/til/638

Sampling in the Field

When sampling in free-flowing streams, water is usually well-mixed, so samples taken near the current will generally represent the stream as a whole. However, in impounded streams or lakes, there is very little mixing. Therefore, it is important to sample away from shore and at different depths, if possible. Go Direct Salinity can be submerged in water for limited periods of time. It has been tested to a depth of one meter for up to 30 minutes. However, submerging the sensor impacts the radio operation by absorbing much of the energy. This may make it difficult or impossible to connect to the sensor while submerged, particularly if there are electrically noisy signals nearby, such as pumps or motors.

Although it is better to take readings at the collection site, salinity readings should not change significantly if you collect samples and take readings later. Just make sure the samples are capped to prevent evaporation. Filling sample bottles to the brim prevents gases like carbon dioxide, which can form ionic species in solution, from dissolving in the water sample. Since the probe has built-in temperature compensation, you can calibrate it in the lab. This means that even though you will be sampling in water at a different temperature than your calibration temperature, the probe will still take accurate readings at the new sampling temperature.

There are no videos for this product.

For many experiments, calibrating Go Direct Salinity is not required. A calibration equation is stored on each Go Direct Salinity before they are shipped, which is used as a default by Vernier software.

For the most accurate measurements with this sensor, especially at the upper limit of the range, we recommend calibration. It is a simple process that takes only a few minutes. For additional calibration information, see www.vernier.com/til/4011

To calibrate the sensor in Graphical Analysis, complete the following steps.

1. Click or tap the sensor meter to view sensor options.
2. Select Calibrate and follow the applicable prompts on the Calibrate Sensor screen.

In order to calibrate Go Direct Salinity, or to confirm that a saved calibration is accurate, you should have a supply of salinity standard solutions that cover the range of the salinity values you will be measuring. For more information about salinity standard solutions, including recipes for preparation, see www.vernier.com/til/20499

Once you have calibrated a Go Direct sensor, the calibration is automatically stored to the sensor and will be used each time you connect to your device. You can always choose to restore factory defaults if you feel the custom calibration is invalid.

To restore factory defaults in Graphical Analysis, complete the following steps.

1. Click or tap the live readouts meter and choose Calibrate.
2. Click or tap Reset Calibration.
3. A window will appear warning you that you are about to reset the calibration. Choose Reset Calibration.

Making Standard Calibration Solutions

If you choose to calibrate the Go Direct Salinity Sensor, you will want an accurate standard solution. Vernier sells a 35 ppt standard solution (order code SAL-ST). To prepare your own 35 ppt standard solution using solid NaCl, use a container with accurate volume markings (e.g., volumetric flask). Add 33.03 g NaCl to enough distilled water to make 1 liter of solution. Use reagent grade NaCl.

Note: The Practical Salinity Scale 1978 was developed relative to a KCl solution. Standard Methods for the Examination of Water and Wastewater states that “A seawater with a conductivity at 15°C equal to that of a KCl solution containing a mass of 32.4356 g in a mass of 1 kg of solution is defined as having a practical salinity of 35.”

Automatic Temperature Compensation

Your Go Direct Salinity Sensor is automatically temperature compensated between temperatures of 5°C and 35°C. Note that the temperature of a solution is being read by a thermistor that extends into the space between the graphite electrodes. Readings are automatically referenced to a salinity value at 25°C. Therefore, the Go Direct Salinity Sensor will give the same reading in a solution that is at 15°C as it would if the same solution were warmed to 25°C. This means you can calibrate your probe in the lab, and then use these stored calibrations to take readings in colder (or warmer) water in a lake or stream. If the probe was not temperature compensated, you would notice a change in the reading as temperature changed, even though the actual ion concentration did not change.

If you want to measure how salinity changes as a function of temperature, you can enable the "Salinity 0% TC" (non-temperature compensated salinity) channel in the software. Additionally, you can enable the temperature channel to obtain precise measurements of the relationship between temperature and salinity. Because salinity measures the total ion concentration, you may want to change the units to μS/cm (microsiemens per centimeter) if you wish to explore this relationship further.

Care and Maintenance

The probe should be stored clean and dry. When you have finished using Go Direct Salinity, simply rinse it off with distilled water and blot it dry using a paper towel or lab wipe. If the entire sensor, including the USB port, has been submerged in salt water, dunk the entire sensor in DI water for rinsing before storage.

If the probe cell surface is contaminated, soak it in water with a mild detergent for 15 minutes. Then soak it in a dilute acid solution (0.1 M hydrochloric acid or 0.5 M acetic acid works well) for another 15 minutes. Then rinse it well with distilled water. Important: Avoid scratching the inside electrode surfaces of the elongated cell.

Important: Do not place the electrode in viscous, organic liquids, such as heavy oils, glycerin (glycerol), or ethylene glycol. Do not place the probe in acetone or other organic solvents, such as pentane or hexane.

Battery Information

Go Direct Salinity contains a small lithium-ion battery in the handle. The system is designed to consume very little power and not put heavy demands on the battery. Although the battery is warranted for one year, the expected battery life should be several years. Replacement batteries are available from Vernier (order code: GDX-BAT-300).

Storage and Maintenance

To store Go Direct Salinity for extended periods of time, put the device in sleep mode by holding the button down for at least three seconds. The red LED will stop flashing to show that the unit is in sleep mode. Over several months, the battery will discharge but will not be damaged. After such storage, charge the device for a few hours, and the unit will be ready to go.

Exposing the battery to temperatures over 35°C (95°F) will reduce its lifespan. If possible, store the device in an area that is not exposed to temperature extremes.

Water Resistance

Go Direct Salinity can be submerged in water for limited periods of time. It has been tested to a depth of one meter for up to 30 minutes. However, submerging the sensor impacts the Bluetooth radio operation by absorbing much of the energy. This may make it difficult or impossible to connect to the sensor while submerged, particularly if there are electrically noisy signals nearby, such as pumps or motors.

Go Direct Salinity measures the ability of a solution to conduct an electric current between two electrodes. In the solution, the current flows by ion transport; therefore, an increasing concentration of ions in the solution results in higher conductivity values. The sensor measures conductance, defined as the reciprocal of resistance. Although the sensor measures conductance, we are interested in determining the conductivity of the solution. A potential difference is applied to the two probe electrodes in the sensor, and the resulting current is proportional to the solution's conductivity. This current is then converted into a voltage for measurement purposes.

To prevent complete ion migration and ensure accurate measurements, an alternating current (AC) is supplied to the electrodes. With each cycle of the AC, the polarity of the electrodes is reversed, which reverses the direction of ion flow (see Figure 1). This critical feature prevents most electrolysis and polarization at the electrodes, ensuring that the solutions being measured do not become fouled. It also significantly reduces the formation of redox products on the electrodes, maintaining the accuracy and longevity of the sensor. To ensure accurate salinity measurements, the sensor compensates for temperature variations, as conductivity typically increases with temperature. A temperature sensor measures the water's temperature, and the data processor adjusts the conductivity reading based on known temperature-conductivity relationships. The adjusted conductivity value is then converted to a salinity value using standard conversion formulas or tables, such as the Practical Salinity Scale (PSS-78). The sensor then displays the salinity value, by default in parts per thousand (ppt), providing a reliable measure of the salinity of the water sample.

When testing Go Direct Salinity, it is best to measure a standard solution because it is easier to determine if the sensor is reading correctly. If your salinity sensor is reading differently from the standard solution, you may simply need to calibrate the sensor. See the Calibrating the Sensor section for more information. Here are some other tips to ensure best data collection practices:

• Blot the inside and outside of the electrode cell dry to avoid water droplets diluting or contaminating the sample to be tested.
• Be sure the electrode surfaces in the elongated cell are completely submerged in the liquid and that there are no bubbles around the electrode surface.
• The probe should be stored clean and dry. When you have finished using Go Direct Salinity, simply rinse it off with distilled water and blot it dry using a paper towel or lab wipe. If the entire sensor, including the USB port, has been submerged in salt water, dunk the entire sensor in DI water for rinsing before storage.
• If the probe cell surface is contaminated, soak it in water with a mild detergent for 15 minutes. Then soak it in a dilute acid solution (0.1 M hydrochloric acid or 0.5 M acetic acid works well) for another 15 minutes. Then rinse it well with distilled water and blot dry. Important: Avoid scratching the inside electrode surfaces of the elongated cell.

For troubleshooting and FAQs, see www.vernier.com/til/20499

If you have watched the related product video(s), followed the troubleshooting steps, and are still having trouble with your Go Direct Sensor, contact Vernier Technical Support at support@vernier.com or call 888-837-6437. Support specialists will work with you to determine if the unit needs to be sent in for repair. At that time, a Return Merchandise Authorization (RMA) number will be issued and instructions will be communicated on how to return the unit for repair.

Item	Order Code
Micro USB Cable	CB-USB-MICRO
Go Direct 300 mAh Replacement Battery	GDX-BAT-300
USB-C to Micro USB Cable	CB-USB-C-MICRO
Salinity Standard Solution	SAL-ST

When disposing of this electronic product, do not treat it as household waste. Its disposal is subject to regulations that vary by country and region. This item should be given to an applicable collection point for the recycling of electrical and electronic equipment. By ensuring that this product is disposed of correctly, you help prevent potential negative consequences on human health or on the environment. The recycling of materials will help to conserve natural resources. For more detailed information about recycling this product, contact your local city office or your disposal service.

Battery recycling information is available at www.call2recycle.org

Do not puncture or expose the battery to excessive heat or flame.

The symbol, shown here, indicates that this product must not be disposed of in a standard waste container.