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HOBO MX2501 MX pH and Temperature Logger Manual 

2

Specifications (continued) 

pH Electrode Life 

6 months 

Memory 

152 KB (43,300 measurements, maximum) 

Full Memory Download Time 

Approximately 60 seconds; may take longer the further the mobile 
device is from the logger 

Dimensions 

22.86 x 4.27 cm (9.0 x 1.68 inches) 

Weight 

268.2 g (9.46 oz) 

Wetted Materials 

Logger: PVC housing and sensor end cap, polycarbonate closure caps 
and mounting end cap with a TPE switch 
pH electrode: plastic-bodied with Pellon® junctions and gel electrolyte, 
glass pH sensor bulb 

Environmental Rating 

IP68 

The CE Marking identifies this product as complying with all relevant 
directives in the European Union (EU). 

See last page 

Logger Components and Operation 

Anti-Biofouling Copper Guard: 

Use this guard to protect the pH 

electrode when deploying the logger in water prone to 
biofouling (see 

Deploying and Mounting the Logger

). 

Closure Caps:

 These caps are screwed onto the sensor end and 

the mounting end (or top end) of the logger. 

Sensor End Cap: 

This is the bottom end of the logger where the 

pH electrode is installed, and the temperature sensor and 
water detection screws are located.

 

Temperature Sensor:

 The temperature sensor is located at the 

base of the sensor end cap. 

Water Detection Screws:

 These two screws on the sensor end 

cap can detect the presence of water. This allows you to 
configure the logger in a power-saving mode in which 
Bluetooth advertising is active only when the logger is removed 
from water. See 

Configuring the Logger

 for details. 

Note:

 The 

logger will check for the presence of water every 15 seconds 

when the Bluetooth Off Water Detect power-saving mode is 
selected. 

pH Electrode: 

This is the electrode that is plugged into the 

logger. The clear plastic end houses a glass pH sensor bulb that 
must always be placed in storage solution when not deployed 
in water. This electrode must be replaced every 6 months. See 

Installing the pH Electrode

 for details. 

Logger Housing: 

This is the main body of the logger. 

Battery Holder:

 This is where one AA battery is installed under 

a battery strap (see 

Battery Information

). 

Reed Switch:

 This is used in conjunction with the magnetic 

switch on the mounting end cap. 

LEDs:

 The blue LED blinks every 4 seconds when the logger is 

logging (unless Show LED is disabled as described in 

Configuring 

the Logger

). The blue LED blinks every 8 seconds if the logger is 

waiting to start logging because it was configured to start “On 

Battery Holder 

Sensor 

End Cap 

Anti-Biofouling 

Copper Guard 

Closure Cap

Closure Cap 

Logger Housing

Mounting 

Hole

Switch 

Reed Switch 

LEDs (Not 

Visible) 

pH Electrode

Water Detection 

Screw (one of two) 

Temperature 

Sensor 

Disassembled logger 

Assembled logger with copper guard installed 

Assembled logger without copper guard installed 

Mounting (or 
Top) End Cap  

Summary of Contents for MX series

Page 1: ...ately 30 5 m 100 ft line of sight in air Wireless Data Standard Bluetooth Low Energy Bluetooth Smart Logging Rate 1 second to 18 hours Logging Modes Fixed interval normal statistics or burst Memory Modes Wrap when full or stop when full Start Modes Immediate push button date time or next interval Stop Modes When memory is full push button date time or after a set logging period Time Accuracy 1 min...

Page 2: ...cap can detect the presence of water This allows you to configure the logger in a power saving mode in which Bluetooth advertising is active only when the logger is removed from water See Configuring the Logger for details Note The logger will check for the presence of water every 15 seconds when the Bluetooth Off Water Detect power saving mode is selected pH Electrode This is the electrode that i...

Page 3: ...ut from the logger without twisting it 2 If this is the first time you re installing a pH electrode skip to step 3 If a pH electrode is currently installed gently remove it from the sensor end cap Use a foam swab dipped in water to clean the internal O rings Use the foam swab to spread a small dot of silicone based grease along both the O rings inside the sensor end cap Do not use a cotton swab as...

Page 4: ... Configure Select logger settings and load them onto the logger to start logging See Configuring the Logger Readout Download logger data See Reading Out the Logger pH Calibration Calibrate the logger following the instructions in HOBOmobile The logger should be calibrated after replacing or cleaning the electrode See Calibrating the Logger Full Status Details Check the battery level and view the c...

Page 5: ... as prompted making sure the sensor end cap temperature sensor and closure cap are submerged in the solution Follow the instructions on the screen Once the pH reading is stable tap Confirm Buffer 10 If you selected three point calibration repeat steps 8 9 11 Tap Save Calibration 12 Rinse the pH sensor with deionized or distilled water again If you will not be deploying the logger immediately attac...

Page 6: ...e Setting up Alarms for more details 7 Tap Start Logging and select when logging will begin Now Logging will begin immediately after tapping Start in the Configure screen On Next Logging Interval Logging will begin at the next even interval as determined by the selected logging interval On Button Push Logging will begin once you press the switch on the logger for 3 seconds On Date Time Logging wil...

Page 7: ...the High Alarm if you want an alarm to trip when the sensor reading rises above the high alarm value Drag the slider to the reading that will trip the alarm or tap the value field and type a specific reading In the example an alarm will trip when the temperature rises above 85 F 5 Enable the Low Alarm if you want an alarm to trip when the sensor reading falls below the low alarm value Drag the sli...

Page 8: ...ensor Limits 5 Enable High Limit if you want burst logging to occur when the sensor reading rises above a specific reading Drag the slider to the reading that will trigger burst logging or tap the value field and type a specific reading In this example the logger will switch to burst logging when the temperature rises above 85 F 6 Enable Low Limit if you want burst logging to occur when the sensor...

Page 9: ...n select Fixed Interval Logging 4 Select Normal to record the current reading for each enabled sensor at the logging interval shown at the top of the screen Do not select this if you only want to log statistics 5 Select the statistics you want the logger to record at each logging interval Maximum Minimum Average and Standard Deviation average is automatically enabled when selecting Standard Deviat...

Page 10: ...ed because the reading was outside the alarm limits or back within range Note Although the reading may have returned to a normal range during logging an alarm cleared event will not be logged if the logger was set up to maintain alarms until reconfigured New Interval The logger has switched to logging at the burst logging rate or back to the normal rate Water Detect The logger has been placed in w...

Page 11: ...s on the sensor end cap shown above Using your finger spread a small dot of grease along both outer O rings Battery Information The logger requires one user replaceable AA 1 5 V alkaline or lithium battery With a logging interval of 1 minute and at 25 C 77 F battery life is 1 year with Bluetooth Always On selected 2 years with Bluetooth Off Water Detect selected and 3 years with Bluetooth Always O...

Page 12: ...nto position 9 Screw the closure cap back on the logger WARNING Do not cut open incinerate heat above 85 C 185 F or recharge the lithium battery The battery may explode if the logger is exposed to extreme heat or conditions that could damage or destroy the battery case Do not dispose of the logger or battery in fire Do not expose the contents of the battery to water Dispose of the battery accordin...

Page 13: ...dustry Canada license exempt RSS standard s Operation is subject to the following two conditions 1 this device may not cause interference and 2 this device must accept any interference including interference that may cause undesired operation of the device Avis de conformité pour l Industrie Canada Le présent appareil est conforme aux CNR d Industrie Canada applicables aux appareils radio exempts ...

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