HOBO Water Temperature Data Loggers for Recording in Water
HOBO waterproof data loggers are widely recognized as the standard for gathering and monitoring water data. Aside from recording environmental conditions these loggers are also predestined for deployment in a variety of industries where harsh conditions are present.
Water often needs to be monitored in hard-to-reach locations. With Onset, you can be sure to have the right products for your water monitoring needs. Key advantages include:
- Simple and quick to deploy
- Fast, easy data offload
- Highly portable and reusable
- Optional water/weatherproof data shuttle
- Suitable for use in oceans, lakes, streams, etc.
Filter YOUR HOBO data logger by selecting from YOUR criteria
Selecting the correct data logger for water temperature measurements
Researchers and resource managers working in the world's rivers, lakes and oceans often need to monitor water temperature over time. Whether they are studying coral reef bleaching, assessing industrial thermal loading in lakes, modeling freshwater fish populations, or developing marine technology, users must have temperature data collection methods that are accurate, reliable, and practical for their particular field sites and studies. Most researchers today rely on electronic underwater temperature logging devices for their monitoring needs, rather than on human data collection. The latest of these loggers are small, rugged, inexpensive, and easy to use. These battery-powered devices can be programmed to gather data for months or years at a time and can withstand an extensive range of environmental conditions, including wide temperature fluctuations, rushing rocky streams, and ocean storms.
Data loggers for monitoring water temperature
Most researchers turn to underwater temperature data loggers to address their monitoring needs. These devices are low-cost, compact instruments with built-in processors, high-accuracy temperature sensing, and battery power in a rugged enclosure designed for long-term underwater deployment. They range from cigarsized units to units the size of a short stack of quarters, typically with anchoring holes at one end.
The latest models feature precision sensors that can measure water temperatures ranging from 0°C to 50°C (32°F to 122°F) in plastic housings and from 0°C to 125°C (32°F to 257°F) in stainless steel or titanium housings. Typically, underwater data loggers are deployed for months at a time, collecting temperature data at user-defined intervals and storing it digitally into logger memory. By operating in a continuous, 24/7 monitoring mode, underwater loggers eliminate many of the hassles of traditional monitoring methods. And, because the devices are typically inexpensive, users are often able to deploy loggers at more points in a water body.
Underwater data loggers also simplify the process of reporting data. Instead of having to manually record times and temperatures, users can simply offload the logger data to a laptop computer and create detailed graphs or tables with the click of a mouse button. The charts can be easily printed or the data can be exported to other software applications as necessary.
Using underwater temperature data loggersWhile specific logger operating procedures vary, the process of using underwater temperature loggers is relatively straightforward and involves three main phases: logger configuration and launch; deployment; and data processing (data retrieval, QA/QC, integration into a database, and analysis).
Configuration and launchA logger is typically configured by connecting it to a computer (with a cable or base station) and making a number of selections:
- Logging interval – This indicates how often the logger will take a water temperature measurement. The frequency of this interval will determine the maximum deployment time for the device.
- Logger start time – This allows the user to start the logger immediately or postpone it until a specific date and time.
DeploymentSeveral steps are involved in deploying an underwater data logger, including site selection, anchoring the logger, documenting logger location, and retrieval. See following pages for specific field tips.
- Site selection – This refers to the particular location in a body of water where temperature sampling is needed. Choose a site with good mixing, such as the turbulent area below a rock. Also make sure that the location will still be submerged at the low water point, and consider potential impact from moving debris
- Anchoring the logger – There are a number of ways to secure underwater data loggers in still, flowing, and marine waters. Some users tether a logger to a cement block or brick using nylon cord, whereas others choose to drive a rebar stake into the streambed or shoreline and tie or clamp a logger to the stake. For deepwater deployment, users usually use plastic cable ties to attach a logger to a mooring line or sand screw. See following pages for more tips specific to certain environments.
- Documenting logger location – To ensure successful retrieval of underwater data loggers, it is important to document the specific location of each one during deployment. This is especially important if more than one person is working with the loggers. Documenting location in at least two ways is recommended, and can be done by taking a photograph of each monitoring site, marking the location on a map or aerial photograph, entering GPS coordinates, and using words to describe the location in a data book. Affixing a “please return to” label to the logger is also a good idea, in the uncommon event that a logger becomes dislodged.
From the field: Tips for deploying underwater temperature loggersLoggers have been launched in a wide variety of field conditions worldwide, and researchers have gained experience in making sure their devices stay put. Here are some notes from the field and factors to consider when deploying loggers in specific environments:
Stream/river/or other shallow deploymentFlowing waters are variable throughout the year and can change even on a daily basis. A logger must be positioned at an adequate depth so that it is always underwater. When choosing sites, take into account incoming tributaries, humangenerated thermal pollution (measure upstream and downstream of inlet), and shading (for sunny sites that are shallow it may be necessary to use a white protective boot or paint on the logger in order to minimize solar heating). In rocky streams and rivers, heavy-duty garden tools are useful for shifting rocks during logger deployment and retrieval.
Ocean and lake deployment (deep water)Wave action, currents, and storms are important considerations when securing data loggers in deep waters. Some users have been successful in anchoring loggers to mooring lines on sand screws or pins (widely available at boating equipment suppliers) driven into solid substrate. Some users attach the logger to the screw or pin itself, and recommend using more than one cable tie in case one breaks loose. In marine environments, a scraping tool is useful if encrusting organisms colonize the logger. In particularly rough conditions, it is wise to secure the entire body of the logger, rather than just one end.
Intertidal deploymentIntertidal environments are alternately submerged in seawater and exposed to the air. They are also subject to wide temperature fluctuations, so logger anchoring materials must be able to withstand such varying conditions. Putty epoxy that cures underwater and in air has been used successfully to anchor loggers to rocks in the intertidal zone
Areas of heavy human use
- Develop your anchoring protocol carefully, and be sure to take into consideration such factors as how you might get a dozen cinder blocks out into a lake or up a mountain stream
- Consider deploying more than one logger per location for data qualitypurposes, or if you suspect you might lose one in a storm or flood.
- Keep in mind that some metal fasteners can corrode quickly, especially in marine environments
- Think about sending two people, instead of one, into the field to locate deployed loggers as this can save time over one person searching alone. This is especially true if a third party deployed the loggers, if they have been deployed for a few months, or if vegetation is heavy or the substrate is rocky.
Data retrieval and analysisAfter temperature data has been collected for a period of time, the next steps involve retrieving, offloading, and analyzing the collected data.
Capabilities to look forThere are a number of features and capabilities to look for when evaluating underwater temperature loggers.First, it is important to make sure that the logger has a rugged, fully-sealed enclosure that will withstand years of use in challenging conditions. Check device temperature and depth ranges, and ask about saltwater deployment, if applicable. For example, stainless steel will corrode when used for long-term saltwater deployment. Protective boots are available from some manufacturers. Secondly, make sure the logger offers suitable options for offloading data at field sites. Dedicated data shuttles allow users to conveniently offload data at field sites without having to worry about moisture getting into a laptop computer. Optical data transfer capability means that data can be downloaded even when the logger is wet. Depending on temperature measurement accuracy requirements and legal requirements, it may be important to choose an underwater data logger from a manufacturer that offers NIST (National Institute of Standards & Technology) testing and certification services. These manufacturers can provide a certificate that indicates the logger’s temperature accuracy versus a NIST-traceable standard.It’s also a good idea to look for loggers that use non-volatile memory that retains data even if battery-power is lost. Finally, the supplied data logger software should enable you to quickly and easily perform tasks such as configuring the logger, and offloading data. If you have multiple loggers to deploy, software features that allow you to batch configure and export data can save a lot of time. The software should also offer powerful data plotting capabilities, and enable you to easily export data to other programs for analysis. Also consider the operating platforms your users have; you may need software that is supported by both Windows and Macintosh operating systems
Conclusion:As the demand for water temperature monitoring grows, so too will the need for instruments that make the process faster, cheaper, and more accurate. Underwater data loggers are the instruments of choice among researchers and resource managers because of their 24/7 operation, high accuracy, ease-of-use, and computer-based analysis and reporting capabilities.