Oxygen Data Logger
Overview
An affordable, precise data logger that measures oxygen concentrations in lakes, streams, rivers, estuaries, and coastal waters. Recommended for aquatic biology and hydrology research projects, this easy-to-maintain logger uses RDO® Basic (Rugged Dissolved Oxygen) optical DO sensor technology.
The HOBO U26 Dissolved Oxygen logger was part of a multi-year evaluation of DO loggers and sensors by the Alliance for Coastal Technologies (ACT), the results of which are published here. This un-biased report describes how the HOBO U26 performs in lab and field conditions. Note that our response letter, with added recommendations, is attached at the end of the report (pages 58-59).
HOBO Dissolved Oxygen Data Logger
Features
- Affordable, high performance dissolved oxygen (DO) monitoring with 0.2 mg/L accuracy
- Optical DO sensor technology for long-lasting calibration with less maintenance
- HOBOware Pro’s Dissolved Oxygen Assistant software corrects for measurement drift from fouling; provides salinity-adjusted DO concentrations and percent saturation
- Optical USB interface for high-speed, reliable data offload
- User-replaceable DO sensor cap eliminates need to send logger back to the factory to replace membrane
NOTE: For DO measurements in saltwater, an adjustment for salinity is required. For waters with small changes in salinity (<2 ppt), a salinity meter reading typically provides enough accuracy. For environments with greater salinity changes, we generally recommend the HOBO U24-002-C Conductivity logger. If you need DO in Percent Saturation, barometric pressure data is required, which can be logged with a HOBO U20-001-04 Water Level logger.
HOBO Dissolved Oxygen Data Logger
Specifications
Dissolved Oxygen
Sensor Type
Optical
Measurement Range
0 to 30 mg/L
Calibrated Range
0 to 20 mg/L; 0 to 35°C (32 to 95°F)
Accuracy
± 0.2 mg/L up to 8 mg/L; ± 0.5 mg/L from 8 to 20 mg/L
Resolution
0.02 mg/L
Response Time
To 90% in less than 2 minutes
DO Sensor Cap Life
6 months, cap expires 7 months after initialization
Temperature
Temperature Measurement/Operating Range
-5 to 40°C (23 to 104°F); non-Freezing
Temperature Accuracy
0.2°C (0.36°F)
Temperature Resolution
0.02°C (0.04°F)
Response Time
To 90% in less than 30 minutes
Logger
Memory
21,700 sets of DO and temperature measurements (64 KB total memory)
Logging Rate
1 minute to 18 hours
Time Accuracy
±1 minute per month at 0 to 50°C (32 to 122°F)
Battery
3.6 V lithium battery; factory replaceable
Battery Life
3 years (at 5 minute logging)
Download Type
Optical
Depth Rating
100 m (328 ft)
Buoyancy
Salt water: 13 g (0.46 oz) negative | Fresh water: 20 g (0.71 oz) negative
Wetted Materials
Black Delrin®, PVC, EPDM o-rings, silicone bronze screws; rated for saltwater use
Size
39.6 mm diameter x 266.7 mm length (1.56 x 10.5 inches)
Weight
272.4 g (9.61 oz)
Environmental Rating
IP68
HOBO Dissolved Oxygen Data Logger
