To size an aeration system for your pond, you will need to determine how many gallons of water it holds and provide it's shape. If you are looking for a turnkey system as opposed to a DIY one, Vertex and Matala are brands that get mentioned here at PB regularly. Essup, a member here will be able to help with a turnkey system or the DIY components. Here's his website...

www.hoosierpondpros.com

If you want to get into the nitty gritty of aeration...supply a satellite image or drawing of the pond with dimensions and depths and we can start noodling a DIY design.

The following area of the PB forums is a great place to get your feet wet on aeration...

https://forums.pondboss.com/ubbthreads.php?ubb=cfrm&c=6