Welcome to the forums Lloyd, you've come to the right place. I, too, am studying aerations systems for my smaller pond. The first thing that you need to estimate is the amount of water in your pond (in gallons). There are pond size calculators out there on the web. Once you have estimated the number of gallons, then you need to size the system to at least one turn over per day. The diffusers should be rated such that they will say how many gallons of water they move (usually per hour). With a little bit of math you can determine how many diffusers of that size and brand you will need to turn your pond over. From there, you back into the pump station. How much pressure and flow does the diffusers you picked out need to operate at the depth of water you intend to install them in, then size the pump accordingly.
There's more to it than that, but that's the basics.
Places found on PondBoss's resource page...
https://www.pondboss.com/Resources?lci=1can make short work of sizing a system. I would suggest talking to Vertex Water Features (at the bottom of the linked page) they were very helpful with sizing the system for my pond and suggested distributors for their systems that were the closest. I ended up doing business with...
http://www.hoosierpondpros.com/to buy the vertex branded aerator supplies.
I found that I could save a few hundred dollars by piecing a system together rather than buying a complete 1$1500 kit, but the trade off is more work for me. It's not really worth it to save 3 or $400, but I like tinkering, so be it. If you don't find the savings that important, I would call a aeration company and let them do the noodling and get it ordered. Otherwise, this forum has plenty of reading and plenty of free advice givers.
