I am new to aeration this year, but I can give you my thoughts...
You need to verify, somehow, that you are turning the pond over enough (once per day)to avoid slowly mixing up lower "stale" water which would constantly be bring up the poisons and O2 absent waters associated with water that would be below a thermocline. I suspect that you are not presenting this problem if you have not been seeing dead fish during it's time of operation, but it is something to verify. What size and type of pump are you using? Do you have a brand name for your diffusers?
Let's assume your system is adequate in turning the pond over at least once a day per the rule of thumb and your location in Kansas will see some cold winter weather. I believe that the aeration should be turned off once the outside air temperatures get below the water temperatures. Your air system should be keeping the water temps pretty consistent from near the surface (5 inches down)all the way down to the diffusers. Let say to within 5 degrees or so. If the outside air temps get below the water temp, the aeration system is effectively cooling the pond down which is unnecessary. I may be splitting hairs here, but winter time aeration seems to be unneeded as colder waters hold O2 better and fish metabolisms slow way down. There is no reason to cool the pond down prematurely as fall sets in. All you will be doing is taking away from the fish's ability to feed during these transition weeks and you could possibly cool the pond down enough to kill the fish if the water gets too cold. Fish will hang out in the deeper warmer waters, but aeration will typically void those warm winter havens.
I was running my summertime air at nights only to avoid heating my small pond up during the day, then I switched to running during the day as air temps at night cooled off below the water temps. Then, I brought my system down over the course of one week by reducing the runtime in half every day as daytime temps dropped below the water temps. Changing up the air schedule really messed with the feeding and fishing, but I felt that avoiding any cooling of the pond was more important.
Just my novice theories, AND welcome to Pond Boss...you have come to the right place!
