General Sensor Questions

AquiStar Smart Sensor Questions

Pumping Questions

General Sensor Questions

What are PSIA (absolute), PSIG (gauge), and PSIS (sealed gauge) pressure sensors and how do they differ?

PSIA (absolute) sensors measure the depth plus the atmospheric pressure. This atmospheric pressure must be subtracted from the absolute pressure to give the actual pressure due to depth. For information on using the Aqua4Plus Barometric Compensation utility to perform these calculations, refer to the Barometric Compensation Utility application note. In addition, the AquiStar Compensator obtains readings from several down-hole sensors, automatically applying barometric compensation.

INW’s PSIG (gauge) sensors utilize a vent tube in the cable to allow the device to reference atmospheric pressure. The resulting gauge pressure measurement reflects only the depth of submergence.

INW also offers a PSIS (sealed gauge) pressure sensor. This is an absolute sensor to which 14.7 PSI offset has been included to account for air pressure. Thus the measurements reflect only the pressure due to depth, when assuming a standard barometric pressure of 14.7 PSI. Measurements with this sensor will vary slightly due to barometric and weather changes.

What is the desiccant tube and what do I do with it?

The desiccant tube prevents moisture in the air from being sucked into the vent tube, which can cause erratic readings and sensor damage. Install the sensor so that the desiccant tube will not flood or lie in water.

The desiccant is a bright blue color when active and dry. As moisture is absorbed the color will begin to fade becoming light pink, indicating full saturation and time to replace. The life of the desiccant varies depending on the environment in which it is installed. The damper the environment or the higher the humidity, the more often the desiccant will need to be replaced. Inspect the desiccant every few weeks, until you know how it responds in your particular environment. Replacement desiccant tubes and desiccant refill bottles can be purchased from INW.

I’m getting erratic readings from my sensor.

Erratic readings can be caused by a poor connection, damaged cable, moisture in the unit, or a damaged sensor. In most cases, erratic readings are due to moisture getting into the system. First check the connection. Look for moisture between contacts or a loose or broken wire. Next, check the cable for cracking or fraying. If the connections and cable appear okay, but the readings are still erratic, the sensor may be damaged. Contact INW for evaluation and repair.

Erratic and erroneous readings can also occur due to improper grounding. See the Grounding Issues application note.

Pressure readings are oscillating over time.

If, after time, your sensor is functioning normally but your data is showing a cyclic effect in the absence of water level changes, you are probably seeing barometric changes. The amount is usually 0.5 to 1.5 feet of water. This can be caused by actual water level changes in the aquifer in response to barometric pressure changes. This effect can occur in tight formations where the sensor will immediately pick up barometric changes but the aquifer will not. If you think you are having this type of problem you will have to record the barometric pressure, as well as the water level pressure and compensate the data.

This can also be caused by a plugged vent tube in the cable. If a desiccant tube is not installed in line with the cable, or if the desiccant is fully saturated, water may have condensed in your vent tube causing it to plug. If it appears that the vent tube is plugged, consult your INW service technician.

My pressure readings are zero.

Continuous zero readings are usually caused by an open circuit, which may indicate a broken cable, a bad connection, or possibly a damaged sensor. Check the connector to see if a wire has become loose or if the cable has been cut. If damage is not readily apparent, contact INW for evaluation and repair.
top of page

AquiStar Smart Sensor Questions

Will Aqua4Plus work on Windows 7 and Windows 8?

Yes, Aqua4Plus works on both Windows 7 and Windows 8.

How can I get the most current software for my AquiStar Smart Sensor?

The most current release of Aqua4Plus can be downloaded from our web site.

Can I read my AquiStar Smart Sensor without the Aqua4Plus software?

Yes. AquiStar Smart Sensors can be read by most Modbus® equipment, directly returning measurement readings, without any further math on the part of the host system. See the Modbus Direct Read application note for details.

Can I read my AquiStar Smart Sensor with a Campbell logger?

Yes, Refer to the Reading AquiStar Smart Sensors with Campbell Loggers application note.

I can’t communicate with my AquiStar Smart Sensor.

Connect your sensor to a USB port on the computer as shown in the diagram below.










If you are using an RS232/serial port, see connection options under Alternate Connection Options in the Aqua4Plus Instruction Manual.

Make sure all cable connections are secure.

Be sure to use Aqua4Plus version 1.9.2 or higher. The newest Aqua4Plus version is available on our Software Download page.

Select USB in the drop-down box on the main window in Aqua4Plus.





Be sure you have installed the USB driver.

  • Most Windows 7 and Windows 8 computers will automatically go to the Internet and download the proper drivers.
  • If you have Windows XP, do not have Internet connectivity, or do not want to access the drivers via the Internet, you can download the drivers from our Software Download page. A copy is also provided on the CD that came with your USB/RS485 cable and on the CD in the Aqua4Plus software packet.
  • See the INW application note USB/RS485 Communication Cable Installation Instructions  for more detailed information.

I have followed the above instructions, but I still do not see USB in the drop-down box on the main window.
  • Click the Start Button on your computer.
  • Right-click on “Computer.”
  • Click on “Manage.”
  • In the left pane, click on “Device Manager.”
  • You may need to update the first driver: In the right panel, under “Other Devices,” you may see a yellow exclamation point next to INW USB Comm. Right-click on this and then select Update Driver Software. This will update the first set of drivers. You should get a message saying that the USB Serial Converter has been installed. Close this window.
  • Now you may need to update the second driver: In the right panel, under “Other Devices,” you may see a yellow exclamation point next to USB Serial Port. Right-click on this and then select Update Driver Software. This will update the second set of drivers. You should get a message saying that the USB Serial Port has been installed. Close this window.
  • Restart Aqua4Plus.
  • See the INW application note USB/RS485 Communication Cable Installation Instructions  for more detailed information.

 My PT2X measures pressure in PSI. How can I change this to feet of water or other units?

In Aqua4Plus, click on the Options menu and then select Display Units. Use this to select the units in which to display our data. This will control how data is represented on the Real Time Monitor, the File Display Window, the Graph Window, and for exported data.

I want to use my PT2X or CT2X to measure water elevation. How do I do this?

The PT2X or CT2X can easily be configured to measure water elevation or depth-to-water. Refer to the Depth-to-Water / Groundwater Elevation application note.

How do I change the batteries in my AquiStar Smart Sensor?

Most AquiStar Smart Sensors use two standard AA Alkaline batteries. To change batteries, the housing for the sensor must be opened. Because there is sensitive electronic circuitry inside the housing, battery changing must be done in a clean, dry environment to avoid contamination or moisture damage to the circuitry.

For details on changing batteries in these sensors, refer to the Changing Batteries in AquiStar Smart Sensors application note.

Can I run my AquiStar Smart Sensor on auxiliary power?

Most AquiStar Smart Sensors come with two AA internal batteries. If auxiliary power is desired, you can use a 6 – 15 VDC supply that can provide 15 mA. Connect to Vaux++ (pin 1 – white) and Ground (pin 5 – blue) or contact INW for auxiliary power supplies.
top of page

Pumping Questions

Where do I put my sensor in relation to my pump?

INW suggests putting the sensor about two feet above the pump. This helps reduce fluctuations in readings due to agitation by the pump. It also allows the sensor to be pulled for calibration, if needed, without having to also pull the pump.
top of page