HOBO MX MX20L-04 (13 ft)

HOBO MX Water Level Data Logger

Bluetooth data offload

A low-cost, research-grade data logger with Bluetooth data offload to continuously monitor water level and temperature. Measures at depths of up to 13, 30, or 100 feet in a wide range of underwater environments, both freshwater and saltwater.

Important Information

Requires a compatible mobile device or Windows computer and the HOBOconnect app. System requirements can be found at the bottom of the HOBOconnect software page.

Overview

The MX20L Water Level Logger brings you all the same great features as the U20L and more!

Integrating Bluetooth for fast and reliable data download, the MX20L logger eliminates the need to plug your logger into a base station or shuttle to offload data in the field, ensuring continuous water level and temperature monitoring. With options to measure at depth ranges of 13, 30, or 100 feet in a wide range of underwater environments, this rugged logger features 0.1% measurement accuracy, a durable polypropylene housing for use in both freshwater and saltwater, and a non-vented design for convenient and reliable deployment.

The MX20L comes with a magnetic activation fob that can “wake up” the logger to activate its Bluetooth communication for configuration and data download. The included fob comes with a lanyard to prevent losing or dropping the fob in the field. You can purchase additional activation fobs HERE.

This logger records absolute pressure, which is later converted to water level readings by our HOBOconnect software. To compensate for barometric pressure changes, you can use another HOBO MX20L Water Level logger as a barometric reference. See our FAQ section for more information.

Features

Self-contained, non-vented design enables easy deployment
Ideal for use in both freshwater and saltwater environments, including wells, streams, lakes, wetlands, and tidal areas
Depth measurement options of up to 13, 30, or 100 feet depending on model
Durable ceramic pressure sensor withstands freezing
Streamlined data offload via Bluetooth to the free HOBOconnect app
HOBOconnect app provides easy extraction and visulization of water level data
Extended battery life up to 10 years (power-saving mode requires magnetic fob to activate Bluetooth for data download)

Specifications

Pressure (Absolute) and Water Level Measurements MX20L-04

Operation Range

0 to 145 kPa (0 to 21 psia); approximately 0 to 4 m (0 to 13 ft) of water depth at sea level, or 0 to 7 m (0 to 23 ft) of water at 3,000 m (10,000 ft) of altitude

Factory Calibrated Range

69 to 145 kPa (10 to 21 psia), 0° to 40°C (32° to 104°F)

Burst Pressure

310 kPa (45 psia) or 18 m (60 ft) Depth

Water Level Accuracy*

Typical error: ±0.1% FS, 0.4 cm (0.013 ft) Water

Maximum error: ±0.2% FS, 0.8 cm (0.026 ft) Water

Raw Pressure Accuracy**

±0.3% FS, 0.43 kPa (0.063 psi) Maximum error

Resolution

<0.014 kPa (0.002 psi), 0.14 cm (0.005 ft) Water

Pressure Response Time (90%)***

<1 second at a stable temperature; measurement accuracy also depends on temperature response time

Temperature Measurements (All Models)

Operation Range

-20° to 50°C

-4° to 122°F

Accuracy

±0.2°C from 0° to 50°C

±0.36°F from 32° to 122°F

Resolution

0.10°C at 25°C

0.18°F at 77°F

Response Time (90%)

10 minutes in water (typical)

Stability (Drift)

0.1°C per year

0.18°F per year

Logger

Wireless Standard

Bluetooth 5 LE

Transmission Range

Approximately 30.5 m (100 ft) line-of-sight

Radio Power

1mW (0 dBm)

Real-time Clock

±1 minute per month 0° to 50°C (32° to 122°F)

Battery

2/3 AA, 3.6 Volt lithium, factory-replaceable

Battery Life (Typical Use)

3 years with 1-minute logging and Bluetooth always on

7 years with 1-minute logging and Bluetooth off and LED off

10 years with 5-minute logging and Bluetooth off and LED off

Battery Indication

Battery status shown in HOBOconnect app (approximate)

Memory (Non-volatile)

Approximately 400,000 sets of pressure and temperature measurements

Data Download Time (with Bluetooth 5+ devices)

Full Memory: Approximately 3.5 minutes

1000,000 measurements < 1 minute

Weight

Approximately 154 g (5.43 oz) in air

Approximately 53.9 g (1.9 oz) in fresh water

Dimensions

3.18 cm (1.25 inches) diameter, 15.24 cm (6.0 inches) length; mounting hole 6.3 mm (0.25 inches) diameter

Wetted Materials

Polypropylene housing and lanyard; Viton and Buna-N O-rings; ceramic sensor in acetal end cap; stainless steel screws suitable for saltwater

Logging Modes

Fixed-interval (normal or statistics), burst or multiple intervals with up to 8 user-defined intervals and durations; logging intervals from 1 second to 18 hours. Refer to the HOBOconnect User’s Guide for details.

Start Modes

Immediate, next interval, date & time, button start (fob or app)

Stop Modes

Memory full, never stop (overwrite oldest data), date & time, or after set logging period

Pause

Pause and restart with HOBOconnect app

Alarms

Log high- or low-alarm events; alarm status shown in HOBOconnect app

Environmental Rating

IP68

* Water Level Accuracy: With accurate reference water level measurement, known water density, accurate barometric compensation data, and a stable temperature environment.

** Raw Pressure Accuracy: Absolute pressure sensor accuracy includes all sensor drift, temperature, and hysteresis-induced errors.

*** Changes in Temperature: Allow 20 minutes in water to achieve full temperature compensation of the pressure sensor. Maximum error due to rapid thermal changes is approximately 0.5%.