Performance Verification Statement for the Hach Hydrolab DS5X and HL4 Dissolved Oxygen Sensors

ATTN: Dr. Tom Johengen

ACT Chief Scientist

CILER- University of Michigan

4840 S. State Stre

Ann Arbor, MI 48

EMAIL ADDRESS:

Date: October 6th

Subject: Hydrolab response to ACT dissolved oxygen sensor evaluation

Dear Dr Johengen,

OTT Hydromet greatly appreciates the opportunity to participate in the thorough technology

evaluation report carried out by Alliance for Coastal Technology (ACT) on the HACH LDO sensor

technology integrated into the Hydrolab multi-parameter sonde platforms. We would like to thank

the entire ACT team for their continued contributions to the advancements of sensor technologies.

As a manufacturer that partners with industry experts to continuously improve both mature and

emerging instruments, we understand the need for rigorous field testing and evaluations in diverse

coastal environments.

Overall we are pleased with the measurement accuracy of the LDO sensors in both the legacy

Hydrolab Series 5 and new HL Series platforms. We always welcome when ACT and similar

organizations drive forward to become early adopters of newer technology platforms such as the

HL4. Although the LDO sensor did perform well there were elements of the sensor evaluation that

helped our organization understand opportunities for improvements in the overall HL4 platform.

The implemented improvements have demonstrated to us and our customers a sustained higher

performance. This commitment to continuous improvement is a cornerstone of our core values.

Thank you again for the important services provided to the environmental monitoring community

and we look forward to working with your team in future evaluation opportunities.

Best Regards,

Ronan O'Maitiu

OTT Hydromet

5600 Lindbergh Drive

Loveland, CO 80538

Email:

romaitiu@otthydromet.com

Phone: (970) 669-3050 x 2571