Onset Introduces pH Data Logger

New HOBO® MX2501 pH and temperature logger wirelessly offloads data to mobile devices via Bluetooth Low Energy to facilitate monitoring of pH levels

BOURNE, MA, July 24, 2018 – The world’s oceans, coastal estuaries, and waterways have seen a 30 percent increase in acidity over the last 200 years, negatively impacting not only coral, but also fish and shellfish that feed more than one billion people. As acidification continues to accelerate, researchers and resource managers are increasing their efforts to monitor these effects. Onset, a world leader in data loggers and weather stations, is making it easier and more cost-effective to address this challenge with today’s introduction of the HOBO® MX2501 pH and temperature data logger.

The new low-cost HOBO MX2501 data logger is designed for long-term pH monitoring in estuaries, lakes, streams, rivers, and oceans. Leveraging Bluetooth® Low Energy (BLE) technology, it communicates wirelessly with the HOBOmobile® app on a user’s phone or tablet—making logger setup, calibration, and data offload quick and easy, with no need for extra equipment. The HOBO MX2501 data logger is lowering barriers for oceanographers, coastal scientists, marine biologists, hydrologists, limnologists, and industrial and facilities managers who need to track acidity levels over time.

“For decades, Onset has been a trusted provider of water quality monitoring equipment that meets the high-accuracy, reliability, and performance demands of environmental research and preservation,” said Insley Haciski, product marketing manager at Onset. “We’re building on this commitment with our new HOBO MX2501 data logger, which addresses the growing need to monitor acidity levels impacting both the environment and the economy. Tapping into the power of mobile technology, our affordable HOBO MX2501 simplifies pH calibration and data collection, making accurate and efficient pH and temperature monitoring more accessible than ever.”

Bluetooth-Enabled Logger Simplifies Data Collection and pH Calibration

By incorporating BLE technology, the HOBO MX2501 data logger dramatically cuts the time and effort needed to collect field data. Users simply remove the loggers from the water to wirelessly access highly-accurate pH and temperature readings, right from their mobile phones or tablets.  

The loggers work with Onset’s free HOBOmobile application for logger setup and data management, enabling users to easily configure the data loggers and manage collected data in real time. Additionally, HOBOmobile’s built-in guided pH calibration feature simplifies an otherwise difficult task by seamlessly walking users through the logger calibration process via on-screen prompts. From their mobile phones or tablets, users also can view data in graphs, check the operational status of loggers, share data files and graph images, and store data in the cloud. There are no cables to manage, no computer software to install, no devices to pair, and no internet access required.

MX2501 Features High Accuracy and Rugged Design

The HOBO MX2501 data logger delivers high pH accuracy of ± 0.10 pH units within ±10°C of temperature at calibration, and a temperature accuracy of ± 0.2°C from -2° to 50°C (28.4° to 122°F). Additionally, it supports water depths of up to 40 m, making it well suited for a range of environments—from small streams to oceans.

Built to be compact and rugged, the HOBO MX2501 logger has a replaceable pH electrode, an anti-biofouling copper guard, and a PVC housing, making it ideal for freshwater or saltwater environments. It also includes a battery-saving water detection feature for long life and less maintenance, making it ideal for long-term monitoring.

Pricing and availability

The HOBO MX2501 pH and temperature logger is available today, with prices starting at $695. The HOBOmobile app for the logger is available as a free download for Apple iOS on the Apple iTunes store. An Android version of the app will be available soon. Additional pricing details and technical specifications for the HOBO MX2501 are available at /products/data-loggers/mx2501.


Onset Computer Corporation
1-800-564-4377 / 508-759-9500

About Onset 

Onset is a leading supplier and trusted manufacturer of data loggers and monitoring solutions used to measure, record, and manage data for improving the environment and preserving the quality of temperature-sensitive products. Based on Cape Cod, Massachusetts, Onset has been designing and manufacturing its products on site since the company's founding in 1981.