Dissolved Oxygen in Water is a Critical Parameter

We Know D.O.

Every species on our planet depends on water and oxygen. For aquatic species, adequate dissolved oxygen is of prime importance to their continued survival. Since dissolved oxygen levels are directly related to good water quality, the two are highly interdependent. Many factors can affect DO levels, and an understanding of these levels in order to make informed decisions concerning wastewater treatment operations, hypoxic zones, aquaculture facilities or large-scale ecosystems is essential.

When it comes to dissolved oxygen measurement, YSI offers more knowledge, more experience and more technology options than any other company. We hope you find this resource page helpful and informative. Visit it frequently. After all, “We Know DO™".

We invite you to download, for free, the very popular The Dissolved Oxygen Handbook.  This resource on dissolved oxygen measurement, dissolved oxygen sensors, and dissolved oxygen data has been a huge hit and you can receive it free. 

Dissolved oxygen measurement in water. DO is often the limiting factor in the health of a thriving ecosystem. Dissolved oxygen testing is quick and simple. Learn more about DO here.

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The Dissolved Oxygen Handbook

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Pioneers in DO


YSI commercialized the first practical dissolved oxygen sensor using the Clark Polarographic electrode in 1962 based on the work of Dr. Leland Clark in conjunction with YSI scientists. This technology became, and still is, the trusted global standard for dissolved oxygen measurement. In 1992, YSI released the patented Rapid Pulse® stirring-independent oxygen sensor which revolutionized the measurement of dissolved oxygen in long-term monitoring applications.

What is a Dissolved Oxygen Meter?

A DO meter measures the amount of oxygen dissolved in an aqueous solution. There are two primary types of dissolved oxygen sensing technologies available: the optical based sensing method which is commonly referred to as luminescent and the Clark electrochemical or membrane-covered electrode. Within these two types of technologies, there are slight variations available. For example, there are two types of optical sensors. Both types of optical sensors measure luminescence as it is affected by the presence of oxygen; however, one sensor measures the lifetime of the luminescence while the other sensor measures the intensity of the luminescence. The two types of electrochemical sensors available are polarographic and galvanic. 


Optical Dissolved Oxygen


In 2005, YSI released its first optical dissolved oxygen sensor that utilized luminescent technology. The wiped ROX® probe significantly increased customer value by reducing costs associated with maintenance, especially when used in long-term monitoring applications.

The ultimate in handheld optical dissolved oxygen measurement can be found on the ProODO®. The ODO® (Optical Dissolved Oxygen) luminescent sensor has no flow dependence making it the perfect choice for applications like deep water profiling where stirring is difficult or undesirable. No flow dependence also reduces the possibility of operator error due to inadequate stirring, ensuring high quality data.  However, stirring, or movement, of the optical DO sensors does improve response time.  YSI may be the only ones who will tell you that.

Essential D.O. Posts on the Blog

What is Affecting Your Dissolved Oxygen Measurements? Part 1 of 4

Dissolved Oxygen Meter Selection - More Than Sensor Technology

Environmental Dissolved Oxygen Values Above 100% Air Saturation

Nonload Parameters in Surface Water | Dissolved Oxygen

Featured Dissolved Oxygen Products

ProODO Optical Dissolved Oxygen Instrument

Optical Dissolved Oxygen Digital Handheld Instrument. Meter Only.


EcoSense ODO200 Optical Dissolved Oxygen Meter Kit

EcoSense Kit with ODO200 Probe and Case

$930.00 - $1,045.00

Pro20 Dissolved Oxygen Instrument

Dissolved Oxygen and Temperature Handheld Instrument. Meter Only.


MultiLab 4010-2

Two channel benchtop multiparameter instrument


Pro1020 Dissolved Oxygen and pH or ORP Instrument

Dissolved Oxygen, pH/mV and Temperature Handheld Instrument. Meter Only.