"Wayne Sallee" wrote in message link.net...
Stoutman wrote on 9/16/2006 12:20 PM:
It is a VERY complex series of events.

Actually it's very simple. Just as we consume oxygen, so
do many types of bacteria. When oxygen levels get low,
bacteria start taking oxygen away from compounds in the
water such as nitrate, nitrite, sulfate, and many other
compounds.

or cyanobacteria consumes free nitrogen where other
algae or bacteria consume nitrates or ammonia.