Welcome to the Dissolve Oxygen Measurement Frequently Asked Questions Page. On this page you can find answers for many general questions.

1. Does temperature affect my D.O. readings?

Yes temperature affects D.O. readings in two ways:

A. It changes the permeability of the membrane. As the temperature increases, so does the permeability of the membrane. As the temperature decreases, the oxygen permeability through the membrane decreases. 

B. The temperature affects the amount of oxygen that can be dissolved in water. As temperature increases, the oxygen saturation point of water decreases. Most meters have Automatic Temperature Compensation (ATC) to compensate for the temperature error due to changes in the permeability of the membrane only. To compensate for saturation changes, use a correction chart. There is a correction chart for fresh water and another for sea water.

2. How should I store my D.O. elctrode?

Store a D.O. probe with the membrane covered by distilled water. Covering the membrane with distilled water prevents the KCl fill solution from evaporating through the membrane.