We need more discussions on water quality.

Theo is the Commissioner of the Better Water Quality League. He only sanctions one water - good aerated water - no skunky water allowed. The Comish is wise -- amen !! \:D

The 2 biggest sources of O2 for a pond are plant/plankton respiration and surface-air interface mixing. If the warm water plankton community's respiration is greatly reduced by cold water and cloudy skies and you get the mixing of low O2 water (cold water sinks until it reaches its greatest density at 39F) the Comish described you may end up with the deadly 15 mins. of reduced DO noted by Bruce.