SKALA AQUALAB 3 System Training

SKALA AQUALAB 3 System Training

AQUALAB 3 Certification Video

Watch the video to become a certified AQUALAB 3 user.  For more detailed information, read the complete user guide below.



SKALA AQUALAB 3 diagram | user manual





Thank you for choosing the AQUALAB 3 from METER Group. The AQUALAB 3 is a water activity meter controlled and operated through the SKALA Mobile by METER application using an Apple® iPad®

Verify all AQUALAB 3 system components are included and appear in good condition:

  • AQUALAB 3 Water Activity Meter with calibrated sensor block
  • AQUALAB Accessory Kit
    •      Verification standards
    •      Power cord (120 V)
    •      USB A to B cable
    •      Sample cups and lids (50)
    •      AQUALAB Cleaning Kit, 1 Year Supply
  • SKALA NEXUS Benchtop Unit
  • SKALA NEXUS Accessory Kit
    •      AC adapter (micro USB)
    •      Ethernet cable (6 ft)
  • iPad STAND
  • Apple iPad (optional)

NOTE: Prior models of AQUALAB 3 are compatible with a SKALA Hub. If setup assistance with a SKALA Hub is needed, please contact Customer Support.

An application called SKALA Mobile by METER, available from the Apple App Store, needs to be downloaded onto the iPad. The app is used to register a new customer, create products and batches, and to operate the equipment. Everything that happens in the SKALA Mobile app goes through SKALA Control. 

SKALA Control is a cloud-based software program where data can be analyzed and downloaded, and where more advanced settings can be made. SKALA Control stores all historic readings, displays readings in charts, modifies customer site settings and users, and modifies existing tests, plus much more. However, SKALA Control cannot operate the equipment or initially register a new customer. 

SKALA training documents and videos can assist when learning how to use SKALA Control.

For more information on SKALA Control, please contact Customer Support.


Please read all instructions before operating the SKALA Mobile app and the AQUALAB 3 to ensure it performs to its full potential.


Follow the instructions below to set up an AQUALAB 3 system.

Connect AQUALAB 3 and NEXUS

  1. Place the AQUALAB 3 on a clean, level surface in a location where the ambient temperature remains relatively constant.

The AQUALAB 3 should be well away from all heating and air conditioning vents, open windows, outside doors, refrigerator exhausts, and other sources of temperature fluctuation.

2. Connect the AQUALAB 3 and NEXUS as shown below.

AQUALAB 3 System Connections

Connect iPad to WiFi Network

  1. Connect the iPad mobile digital device to the WiFi network (not cellular). 

NOTE: The NEXUS and iPad must be connected to the same local area network. These networks must also be able to communicate with SKALA’s cloud-based servers.

2. Ensure iPad is associated with the appropriate Apple ID.

Download SKALA Mobile by METER to the Apple iPad

  1. Use the iPad camera to scan the QR code on the back of the NEXUS device. This will open the Apple App Store.



2. Download the SKALA Mobile by METER app.



NOTE: The application can also be found by searching for SKALA Mobile by METER in the Apple App Store.

When setting up the AQUALAB 3 system for the first time, setup wizard goes through the steps to Register Company, Connect NEXUS, and Create Products. The wizard is only available for the first setup. After that, these steps can be done from the app menu. Below is an image showing the setup wizard tabs. 



If the iPad goes to sleep during initial system setup, SKALA Mobile will close. Alter the iPad Display Auto-Lock settings to the desired length of time to keep SKALA Mobile active. Section 2.2 details how to log back into the app. 

Register New Company

  1. Open SKALA Mobile.

2. Register a new company as explained below.

a. Press the Register Company button on the left side of the window (shown below) on the iPad touch screen.

If the company is already registered, enter the username and password in the fields on the right and press the Sign In button.



b. Enter company information in Register Company window.



c. Enter administrator account information.



d. Press the Register button at the bottom of the screen (not shown).

e. Connect mobile phone.

-Enter a mobile phone number in the Connect Mobile Phone dialog window and press Send SMS.



A Token Verification dialog window will appear and a 4-digit code will be texted to the mobile phone.

-Enter the Token Verification code that is texted to the mobile phone. 

-Press the Verify button.



The following instructions explain how to use the setup wizard to register the NEXUS. 

  1. Press OK in the Register NEXUS dialog window.

If an error message appears, contact Customer Support.


2. Press the blue plus sign in the lower right corner of the screen to add a NEXUS.

A Register NEXUS dialog will appear.



3. Press OK.

The iPad camera app will open and a dialog will appear asking for permission to access
the camera. 

4. Press OK in the dialog window to give SKALA access to the iPad’s camera. 



5. Turn the NEXUS over and place the QR code in front of the camera window and inside the green box as shown in the image below.



When the camera recognizes the QR code, SKALA Mobile will automatically register the QR Code. A dialog like the one shown below will appear indicating Registration success!



6. Press OK.

The AQUALAB 3 system is now ready to add product and batch information. Please contact Customer Support if experiencing problems registering a NEXUS.

Register Additional NEXUSes

If another NEXUS or additional NEXUSes need to be set up, please do the following:

  1. Open the SKALA Mobile app menu located in the upper left corner of the screen.



2. Select NEXUS under Setup. 

This will open the following window with a list of currently registered NEXUSes.



3. Press the plus symbol in the bottom right corner of the screen to register another NEXUS. 

4. The registration process will start at step 2 in the previous Register NEXUS section.

Verify NEXUS Is Online

To verify that the AQUALAB 3 system is able to locate registered NEXUSES, open the NEXUS window from the SKALA Mobile app menu. Any NEXUS devices should be listed here when they are properly registered and online. Please contact Customer Support if experiencing problems registering a NEXUS. 


To re-enter the SKALA Mobile app if the iPad goes to sleep, enter the following information. 

  1. Select User Name. 

When the Select User Name field is activated, a list of available usernames will appear in a drop-down list.

2. Enter 4-digit pin.

3. Press the Login button.



A product that will be tested must be created in the SKALA Mobile app before tests can be run. Products can also be added at any time from the Products page (see Add Additional Products). Products must be added prior to adding a batch.

Add a Product

Use the following steps to set up a product using the SKALA Mobile app wizard. 

  1. Press the plus sign in the blue circle in the bottom right corner of the window to add a product.



2. Enter product information and required test specifications.



3. Press Add product when all required information is entered.

NOTE: Water activity tests are always available. Additional tests can be added when subscribed to a premium plan. Learn more about SKALA plans at metergroup.com/skala-upgrade.

The following window will appear once a Product has been added.



Please contact Customer Support if experiencing problems.

Add Additional Products

Instructions explaining how to add additional Products are listed below.

  1. Open the SKALA Mobile app menu by pressing the menu icon located in the upper left corner of the screen.



2. Select Products under Setup.

This will open the Products window.



3. Tap on the main screen (white or gray area) area right of the menu to close the menu.



4. Press the plus symbol in the bottom right corner of the screen to add a new Product. 

5. The process of adding a new Product will start at step 2 in Add Additional Products.

Remove Products

If Products need to be removed, please follow the steps below:

  1. Open the SKALA Mobile app menu by pressing the menu icon located in the upper left corner of the screen.



2. Press Products listed under Setup.

A screen similar to the one below will appear. 



3. Press on the garbage can icon to remove the Product.

A dialog window like the one below will appear.



4. Press the Remove button. 

Please contact Customer Support if experiencing any problems adding or removing Products.


The following steps explain how to add a batch.

  1. Open the SKALA Mobile app menu by pressing the menu icon located in the upper left corner of the screen.



2. Press Batches listed under Monitoring at the top of the menu.

This will open the Batches screen.



3. Tap on the main screen (white or gray area) area right of the menu to close the menu.

4. Press the plus sign in the blue circle in the bottom right corner of window to add a Batch.



5. Enter the  following Batch information in the Add a new Batch dialog window that appears.

a. Select the product. 

b. Enter a batch number.

c. Days Active—number of days visible in SKALA Mobile. After that, the batch can be accessed in SKALA Control.

d. Line Number—identifies specific customer selected process line.



6. Press Add batch to save the new batch information. 

A screen similar to the one shown below will appear.



The SKALA Mobile app handles the entire interface for setting up and taking readings with the AQUALAB 3. 

Before testing a sample, ensure that the AQUALAB 3 has warmed up for at least 30 min and that the sample chamber and cover are clean and dry.

NOTE: SKALA Mobile will prompt the user to verify the calibration of the AQUALAB 3 according to the frequency established by the administrator in SKALA Control.

  1. Open the SKALA Mobile app menu by pressing the Menu icon located in the upper left corner of the screen.



2. Press Batches listed under Monitoring at the top of the menu.

This will open the Batches screen.



3. Press the right-pointing arrow at the far right of the batch to be tested listed on the Batches screen.



4. Press the plus sign in the lower left corner of the screen to create a sample to test.



5. Press the Add sample button.



6. Press the TAKE READING button to start the reading process.



NOTE: Products must be added to the SKALA Mobile app before tests can be run (Managing Products).

7. Choose an available instrument to start a reading.



NOTE: If no instrument is listed, please see Troubleshooting.

On the selected AQUALAB 3 instrument, the indicator light will turn blue and spin counter-clockwise, indicating that the system is ready to collect a reading. 



8. Press Start on the Take Reading dialog box to start the reading if the sample is already loaded and the drawer knob is turned to the left.



NOTE: If the sample has not been loaded into the sample drawing, continue with the following steps. 

9. Prepare the sample using clean sampling practices to ensure accurate and repeatable readings. Wash hands thoroughly or put gloves on prior to using the instrument. See Cleaning for detailed cleaning methods.

a. Fill the sample cup enough to cover the bottom but no more than half full.




b. Clean sample cup bottom, sides, and rim thoroughly with KIMWIPES® strips. 

Keep samples in sealed packaging or in a sample cup with a sample cup lid when a sample is not actively being read. Otherwise, the sample water activity will slowly equilibrate with the humidity in the ambient air.

NOTE:   If the sample will be sitting for more than 2 h before being read, seal the sample cup edges with a piece of parafilm or a similar material.

6. Insert the sample cup into the AQUALAB 3 sample chamber:

-Pull the sample drawer out.

-Lift the sample cover.

-Place the sample cup (without the sample cup lid) into the sample chamber.

-Lower the sample cover down over the sample cup, and push the drawer closed.

-Turn the drawer knob counter-clockwise to the Closed position to begin the reading.

This will automatically start the test.

NOTE: Turning the draw knob clockwise or opening the drawer before the test has been completed will cancel the test.


The AQUALAB 3 will start the reading and slow pulsing blue light will show on the AQUALAB 3 while the reading is in progress. A Reading in Progress message will appear on the app screen.



Press the In-Progress Readings button at the bottom of the app screen to see the In-Progress Readings dialog window with the reading status. 

Press the Close button to close the In-Progress dialog window and return to the readings window. 



7. When the reading is finished, a dialog box will appear in SKALA Mobile with test details.

The AQUALAB 3 indicator light will turn either a solid green, yellow, or red, indicating the knob should be turned towards the Open position. The color signal corresponds to the reading received and should match the result in the SKALA Mobile dialog.



-Solid green indicates the reading is within defined operational limits.



-Solid yellow indicates the reading is outside of defined operational limits but within defined fail limits.



-Solid red indicates that the reading is outside of defined fail limits.



-Flashing red indicates there is an error associated with the AQUALAB 3. 

The SKALA Mobile should indicate what the error is and how to fix the error. If the error is not actionable by the user, the message will be to contact Customer Support.

See Troubleshooting for information on what to do if the indicator light is red.

8. Turn the drawer knob clockwise and open the drawer.

The reading data will automatically be saved in SKALA Control with the associated product batch and information about the instrument used to test the sample.

The image below shows old batch readings displayed in SKALA mobile app on the iPad.



The AQUALAB 3 reports the reading when equilibrium is reached; for many products, equilibrium will occur in 5 min or less. However, some types of products may take longer, such as products with

  • a moisture barrier (e.g., whole seeds and nuts),
  • a high fat content (e.g., peanut butter),
  • extremely low water activity, or
  • multiple components (e.g., cakes with filling, cheese and crackers, cereal with fruit).

Contact Customer Support to help determine if the product requires longer read times and if any actions may shorten the read time.


Water activity
Sensor typeChilled mirror dewpoint
Range0.030–1.000 aw
Resolution0.0001 aw
Accuracy±0.005 aw
Repeatability0.002 aw
Operating Temperature
Controlled at constant25 ºC
Resolution0.1 ºC
Accuracy±0.1 ºC
Read Timetypically 5 min
Case dimensions
Length9.2 in (23.4 cm)
Width9.2 in (23.4 cm)
Height5.04 in (12.1 cm)
Case materialPolycarbonate-ABS (PC-ABS)
Weight11 lbs (5 kg)
Display2388-by-1668-pixel resolution at 264 pixels per inch (ppi) (11 in)
Operating temperature15–35 ºC
Operating environment0%–90% noncondensing
Sample Dish Capacity7.5 mL recommended (15 mL full)
Power110–240 VAC

47/63 Hz (Fuse 2 A @ 250 V)




Verification tests to validate instrument accuracy should be performed once per day or once per shift when the AQUALAB 3 is in use. Verification schedules and the selection of verification standards to use are set in SKALA Control.

The best way to verify the AQUALAB 3 is to use a technique called bracketing, which uses the verification standards of the closest higher and lower values to the expected water activity of the product. If measuring a cookie that typically has a water activity of 0.60 aw, use the 0.500 aw and 0.760 aw standards to verify. If measuring milk powder with 0.300 aw, use the 0.250 aw and 0.500 aw standards to verify. SKALA Mobile will display prompts to run a verification according to the set schedule and using the specified standards.

When SKALA Mobile indicates a verification is needed, perform a manual verification. Follow the steps listed below.

  1. Wash hands thoroughly or put on lab gloves.
  2. Prepare standard.

NOTE: The standard should be prepared outside of the sample chamber to avoid contaminating the chamber by spilling standard. 

a. Check the expiration date of the standards solution.

The typical shelf life of standards is 18 months. Expired standards should not be used for verification.

b. Read the standards in the order of increasing water activity if using more than one standard. 

c. Remove the cap on the standard vial by twisting counter clockwise.

d. Empty the vial contents into a sample cup. 

The standard should cover the bottom of the cup.

e. Place the standard cup in the sample chamber. 

f. Close the sample drawer and turn the knob to the left to lock the drawer.

NOTE: Do not contaminate the sample chamber by spilling standard inside the sample chamber.

3. In the SKALA mobile app, navigate to the Instruments page.



4. Press VERIFY located at the far right of the AQUALAB 3 line.



The Instrument Verification dialog window will appear.

5. Follow the directions on the Clean Device tab to make sure the sample drawer and sensor block are clean (Cleaning).



6. Press the Next button.

The standard tab will appear. The tab heading will show the selected standard for the verification test.



If an error message indicates there are no assigned standards for the instrument, go to skalacontrol.com and select a standard to use.

7. Prepare the standard and AQUALAB 3 to take the verification reading. 

a. Insert the standard in the sample chamber.

b. Close the sample cover.

c. Push the sample drawer in.

d. Turn the drawer knob counter-clockwise (left) to close the drawer.

8. Press the Start button on the SKALA Mobile app screen to start the reading. 



9. Press the In-Process Readings button at the bottom of the Take a Reading window to see the progress of readings.  



10. When the verification reading is finished, a dialog window will appear in SKALA Mobile with the results of the reading. Below are explanations of the different screens that will appear.

a. If the reading is within ±0.005 aw of the standard value, the calibration has been verified, and the AQUALAB 3 is ready to begin taking readings. 


b. If the reading is more than ±0.005 aw but less than ±0.03 of the standard value, the user will be asked if an offset should be applied. 

Apply an offset only if the instrument has been cleaned thoroughly prior to verification.



c. If the reading is more than ± 0.03 aw of the standard value, SKALA mobile app will display instructions to clean the AQUALAB 3 and retry the verification.



If the value consistently fails (is greater than ± 0.03 aw out of specification) with the correct standard, contact Customer Support for assistance.


It is extremely important to keep the instrument clean to make sure it is performing accurately. It should be cleaned when contamination is seen. However, some types of contamination are not visible. The best way to check for contamination is by running verification standards daily or at the start of each shift. If the verification standards are not within specification, cleaning the AQUALAB 3 sensor block is recommended. The AQUALAB 3 comes with a cleaning kit that contains the following items:

  • Cleaning swabs
  • KIMWIPES strips (1.25 in)
  • Cleaning solution (in bottle with white lid)
  • Deionized water (in bottle with blue lid)

NOTE:   Regulations regarding hazardous materials prevent METER from shipping isopropyl alcohol in the cleaning kits, but it is often the best cleaning agent, particularly when measuring samples with a high fat content.

Use the following process to clean the AQUALAB 3.

1. Power off the AQUALAB 3 and disconnect the SKALA NEXUS.

2. Put on lab gloves.

3. Wipe the drawer and detachable sample cover clean, making sure no sample residue remains.

Ensure that the sample cover and drawer are thoroughly dried prior to measurement.

4. Lift off the top of the AQUALAB 3 to expose the interior.

Only the sensor block and ribbon cable will be visible.



5. Pull out on the side tabs to unplug the ribbon cable.

6. Loosen the thumbscrews and lift sensor block to remove.

NOTE: The block has been designed to be ESD resistant, however, care should be taken when cleaning and handling the AQUALAB 3 block.



7. Turn the sensor block over so the sensor chamber area is visible, and clean the sensors and sensor block.

a. Wrap a KIMWIPES strip around a cleaning swab by folding the wipe over the head and twisting the swab until reaching the end of the strip.

Click on the AQUALAB Cleaning Kit image below to view a video showing how to wrap a KIMWIPES strip around the cleaning swab.

NOTE:   Fully cover the cleaning swab with the tissue to avoid scratching the components and surface of the chamber.


b. Moisten the KIMWIPES strip with cleaning solution or isopropyl alcohol (concentration greater than 90% recommended).

To avoid contamination, do not dip a used KIMWIPES strip into the cleaning solution or alcohol.

c. Clean the mirror, optical sensor, and thermopile by gently wiping the KIMWIPES strips over the sensors.

NOTE:   Do not put too much pressure on the thermopile sensor, the mirror, or optical sensor.



Discard used KIMWIPES strips frequently during the cleaning process to get each component clean.

NOTE:   Use the KIMWIPES strips supplied in the cleaning kit rather than facial tissue, paper towels, or commercial swabs. KIMWIPES strips are specially made for lab work. They do not contain adhesives or other contaminants and are made from low-lint fibers that will not scratch delicate surfaces when wet.

d. With additional moistened KIMWIPES strips, clean the remaining surfaces of the sensor block without wiping the KIMWIPES strips back over the sensors.

8. Moisten a fresh KIMWIPES strip wrapped around the cleaning swab with deionized water.

9. Clean the sensors and sensor block, following the same procedure outlined in step 7. To avoid cross-contamination, do not dip used KIMWIPES strips into clean distilled water.

10. Use fresh dry KIMWIPES strips wrapped around the cleaning swab to remove moisture on the sensors and in the sensor block.



Most instrument problems are directly related to contamination in the sensor chamber. Refer to Cleaning for instructions on cleaning the instrument.

No AQUALAB 3 available
in the app when trying to take reading.
  • Make sure the AQUALAB 3 is properly connected to all wires and the power indicator is in the ON position.
  • Make sure the NEXUS is properly connected to all wires and the power indicator light is ON.
  • Make sure the iPad and NEXUS are connected to the same local area network (LAN). 


  • Disconnect and reconnect the NEXUS and the AQUALAB 3 to reboot them. Wait a few minutes for the NEXUS to reestablish an Ethernet connection. 
  • If the AQUALAB 3 still does not appear, contact Customer Support.
Readings are slow
or inconsistent.
  • The sample chamber may be dirty.
    Clean the instrument according to instructions (Cleaning).
  • The temperature difference between the sample and the instrument may be too large.

    The sample needs to equilibrate to instrument temperature before an accurate reading can be made. Let the sample sit in a covered sample cup in the area where readings will be taken until it is at room temperature. Covering the sample minimizes exposure to ambient humidity, which can affect the water activity of the sample. Samples can also be equilibrated to a specific temperature with a Temperature Equilibration Plate, which can be purchased from METER.
  • The product sample may be low emitting.

Some products absorb or desorb moisture very slowly, causing measurements to take longer than usual. Although these samples will always take longer to come to vapor equilibrium inside the sample chamber, Customer Support can provide strategies to help speed up read times.

The device is not
reading correctly.
  • Make sure that clean sampling practices (Cleaning) are being followed and that standards solutions have not expired.
  • Check if the product being tested has special properties that need special consideration. Volatile compounds will affect the water activity readings of the AQUALAB 3. If products being tested contain volatiles, contact Customer Support for further assistance.
  • Verify that the o-ring is seated properly by removing the sensor block and inspecting it.
There are no assigned standards for instrument verification. Please assign a standard to instrument in SKALA Control, and try again.
  • Go to skalacontrol.com and select a standard to use in verification of the instrument.
AQUALAB 3 indicator light is red.
  • Instrument needs to be calibrated. Contact Customer Support for more information.



Customer support representatives are available for questions, problems, or feedback Monday through Friday, 7:00 am to 5:00 pm Pacific time.
Customer support representatives are available for questions, problems, or feedback Monday through Friday, 8:00 to 17:00 Central European time.
Phone:+49 89 12 66 52 0
Fax:+49 89 12 66 52 20


If contacting METER by email, please include the following information:




Phone number

Email address

Instrument serial number

Description of problem


NOTE:   For instruments purchased through a distributor, please contact the distributor directly for assistance.


KIMWIPES® is a registered trademark of Kimberly-Clark Worldwide, Inc. Used with permission.

Back to Top

AQUALAB 3 Video Training

How to Log In


How to Add Users


How to View Readings


How To View Record Details


How to Approve Records


How to View Verification Records


How to Update Verification Requirements


How to Generate a Certificate of Analysis