Rainbow trout, Brook trout, and fathead minnows are currently in my 14 foot deep pond. 0.6 acres currently running 24/7 aeration with 2 diffusers. For recommended winter aeration, I was all set to turn off the deep water diffuser to prevent super-cooling and keep the shallow water diffuser running in 3 to 4 feet of water for a hole in the ice. Then, I read this thread:

https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=478466#Post478466

Cody mentions that trout can tolerate super-cooled water and the extra DO from the deep water diffuser is a good thing.

Now I am confused on which way to go. Keep the diffusers as they are and super-cool the deep water, or not?

Also, when do you change over to a winter shallow water only aeration scheme? When ice is likely to form and linger, or at a specific water temperature? My water is currently 54 deg F. The weather forecast for next week is lows in the mid 20's, highs of 40. If I do the winter scheme, I am thinking to change over now.

I've had trout in my pond for the winter for a number of years.BUT I also have other species of fish. I have just run the diffuser in shallow water and have seen no downside to it.

Just remember the word "tolerate". Trout grow best around 50°F, the further away from that you get the slower they grow.

For your mid Michigan location during winter, I would move one or both diffuser/s toward the shore so the water boil daily creates some open water close to shore and outward as far as the open area advances. This could mean the aerator would run 3 -5 hrs per day. During ice cover when water is cold the currents spread much easier and much further compared to summer conditions.

This means probably during your Michigan winter the diffuser/s sit in 4ft - 6ft deep. Some ice can develop or remain a foot or 2 along the shore during aerator on periods. During daily aerator off periods ice will reform on the open water. Refreezing of clear clean ice of the open water zone allows sunlight penetration and good dissolved oxygen production by phytoplankton and bottom benthic algae. I think you want the aerator action to create an open water area close enough to shore so on sunny days you can toss some food pellets into the open water area. In heavy snow and near 0F conditions, I think you need to run the diffusers just enough to create the "regular" size of open water area that might usually be 20X50ft. As long as the trout will eat some pellets during open water periods, "super cool" water is not a big factor for the trout. Let the trout be your indicators for acceptable water temperature. Results this 2023-24 winter aerator operation will determine future winter aeration placement and techniques.

Trout stay active and healthy in winter in streams that form anchor ice which means water significantly colder than 39F and close to 32F. Google: anchor ice formation.

For me, the biggest factors in where the winter diffusers are set during the winter are 2-fold. First and biggest criteria for me is will there be open water all the way to shore? 2nd criteria is having it shallow enough so it doesn't super cool the water but none of the customers have a trout only pond.

I almost lost 2 of my Springer Spaniels in the pond one very cold winter. I had the winter diffuser set out 70 feet from shore but still where it was 1/3 the total pond depth. I let the dogs out to go potty and I guess they heard a goose on the pond. They were out there for about 10 min when I called them back. The female came up to the house with a Toulouse goose in her mouth. She got that from the pond (she was wet, as well as her brother). I took it from her, tucked it under my arm, grabbed it's bill so I wouldn't get bit and put her and her brother in the laundry room. I walked out behind the barn by the pond and let it go. It indignantly waddled to the pond, went back in the open water to a Canada goose that was in the open water that didn't fly away. (It turned out that it had a broken wing and couldn't fly.)

Fast forward a week. Temps went from upper 20's the previous week to -10°F with 20 mph winds. I had forgotten about the goose incident and let them out again to go potty. This time when I called them they didn't come back. Crap. Put on the winter jacket and hat, and walk towards the pond. As soon as I rounded the corner of the barn I ran to the pond. They were very well trained and I whistled for then to leave the geese alone and come here. They were so cold that they couldn't get out of the pond and up onto the ice. I couldn't go out and get them because the ice was only a few inches thick and nobody was around to help. I could see ice forming in the fur on top of their heads. I ran to the barn, got an extension ladder and ran back to the pond.

I used the extension ladder to break the ice enough that there was a path to the open water from shore, but there was still a foot or so of ice that I couldn't hit with the ladder. Luckily when I called them to come and leave the birds alone, they were able to break that ice and start swimming to shore. About 5 feet from shore and in about 4 feet of water Dottie (the Female) happened to put her paw on Cal's (the male) head. Down he went under the water. I was able to grab her, threw her out of the pond and told her to sit/stay. I turned around and Cal still wasn't up to the surface. I was about to go in after him when he popped up. I grabbed him, threw him up on the bank, told them to heel and started for the house. Cal was so cold that he walked all hunched over. They had ice in their fur and were shivering. Dottie still wanted to go after the geese and I had to remind her a few times NO, HEEL.

I threw them in the laundry room, turned the shower on and ripped off my clothes. I almost had to carry Cal to the bathroom, threw both of them in the shower and climbed in after them. I adjusted the water so it wasn't too hot - I figured if I could tolerate it so could they. It took 20 minutes in the shower with me moving the shower wand (I had it on a 2x long hose) over both dogs before they stopped shivering. I kept them in there for another 10 minutes, then got out and dried them off.

After that incident I moved the diffuser about 30-40 feet closer to shore. Now ANY aeration system that we install or ANY aeration system that we service at a customers house where the ponds will freeze we make dang sure that the winter diffuser is placed so anything that goes in the water during the winter does NOT have to climb up on the ice to get out of the pond. Lesson learned, almost the hard way. That's not anything that I want to repeat, nor have a customer have that happen to them (or one of their kids).

Bill and esshup, thanks for the info.

When do you switch over to winter aeration?

Good story, esshup!

There are frequent comments on Pond Boss about making an area of the shoreline slope shallow enough that humans and animals can walk out of the pond.

I have never heard any consideration of making the open water/soft ice areas reach all of the way to the shore.

Probably a good warning to broadcast since lots of my northern buddies love to do winter sports out on the ice. It would certainly be a tragedy to lose a human or a dog because they couldn't get back out of the pond after falling through the ice.

The recommendations from the aeration companies is to NOT go on the ice if you aerate in the winter. I am not going to say otherwise.