CSCS, With what you said regarding the size of your pond and the overall depth I would think it's fair to say that you have 1/4 ac @ 3-4 feet and 1/4 ac @ 5-8 ft, correct? If that's the case or the depth is split by a dropoff or ledge, then all you really have to focus your efforts on is the portion that's 5-8' or 1/4 ac. Whether you choose a bottom based aeration system or fountain is really up to your expectations of the pond and your budget. Dantheman was correct saying that bottom aeration is effective and that fountains do lose alot to evaporation, but in somewhat less rain dependent areas like LA that may not be as big of a factor.
If the pond is heavily stocked AND you are feeding heavily I say bottom aeration is the route to take. High effeciency due to depth, long bubble contact time and a large DO demand from the fish. A package with three diffuser manifolds would be excessive, you should only really need one with 1/4 at that depth. If you like the idea of a fountain, we have a bottom drawing fountain that provides good circulation and decent aeration values.
If you would like to talk about specifics send me a private message.
