temperature affects D.O. readings in two ways:
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
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