Reaerating Media

If the media is left to stand in the air it will reaerate over a period of several hours. The rate of reaeration is largely dependent on the temperature of the media and its agitation. Media that is stirred by a paddle has a reaeration rate of ~3mg/l over 120 minutes. This compares to ~2mg/l for 100rpm paddles and 1.5mg/l for media that is left to stand. It is important to fill the vessels carefully — if the liquid is slowly transferred to the vessel, without splashing, the level of air will increase by around 0.5mg/l. If it is just splashed in it will increase by roughly double this value.

The speed of reaeration slows as it approaches saturation level and should not form bubbles for the duration of the test.