The more organic matter there is in a pond, the more bacteria is in there to decompose the organics and the bacteria chew up a bunch of O2.

As for aeration. Grid based, shallow water for winter, deep water for summer if the water is deeper than 10'. If you want help designing a system we do that and also sell them. We sent a lot of supplies out to a pond owner near Montrose, Co.

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).