Monty,
Sounds like you have a very cool pond! Well I am no "professional" in the realm of air that's for sure. Bill makes a good point. Get advice from every direction you can. There are a lot of guys on this site that know about air, and each pond is in some way different. For example I have a air system that works quite well for those ponds of basic shape and contour of 1 acre or less. With that said that doesn't mean you can take that system and just double it and put it in a 2 acre pond. Lots of variables there to examine. Like Mr. Cody said you may want to put a fuser or 2 in them deep spots to keep them turning a flow. That's a very cool idea by the way Bill. Bottom line is this. There are a LOT of things to look at and figure out when it comes to air. Like pump type, pump size, how many pumps? Type of air hose to use, how much CFM will my pump push out at what depth? What's the min and max my diffusers can handle CFM wise. I will use this for an example for you.
Take for example my setup. I have a pump that will produce a max CFM of 7. And a max air pressure of 5.1. Well if I remember right you will lose about 1psi for about every 2.5 feet or so of water downforce and my system is in 8 feet. So at 8 feet my system is producing about 2 to 2.2 psi. Which is fine it doesn't have to produce a whole lot to get the job done. Just remember you don't want to push your pump to the edge all the time either or it won't last long.
Ok so now I have my pump it's pushing out about 2 psi and remember I have a max CFM range of 7 also. This CFM range you will have to find out from a pump chart or from the person you buy your pump from, because the chart is going to let you know how many CFM's the pump will put out at what depth. So lets say your CFM end up being 5 at 15 feet. Well ok now you have to figure in what's the CFM range of my diffusers I am using.
For example: I have 3 diffusers that will work anywhere from .5 CFM to 5 CFM each. So if your pump is putting out 5 CFM that means I would have about 1.7 CFM going to each diffuser which is in range and your good. I hope this all doesn't make your brain fry!
Don't over think it you just need to know a few things on the front end to make your setup work like you want it to and your good to go.
