Coondog,
I'm here in northeast Indiana too near a town called Ligonier. There are all kinds of possibilities.
If you want to stop in a place to see them visually and purchase on site both the Finfarm in Ridgeville Corners Ohio (east of the Indiana line about 45 minutes on Rt. 6, or Bill Cody east of that just south of Rt. 6.
You can also order through a catalog or on the Internet and the best prices I have seen are Stoney Creek Equipment Company in Grant Michigan.
Here are web sites or contact numbers etc.:
http://www.ridgeviewfinfarm.com/ Bill Cody, Malinta Ohio
(419) 256 -7433
Stoney Creek Equipment Company
http://www.stoneycreekequip.com/ Remember if you are setting up a diffuser system you may want to run it only a short time everyday and increase gradually to full-time if your water is now stratified. You could bring up some low oxygen water too fast this time of year (especially later in the summer), and have a fish kill. Talk to one of the dealers and get all the information you can and do it right.