Pond Boss Forums Thread Like Summary - Aeration for Fall and Winter

Quick question about when and how long I should run the aerator in the fall and winter. I read on here during the summer to only run it at night so my water didn't get too warm. That was helpful. Now that it's gotten cooler, I figure I should change it up. I assume I'll have to run it 24/7 to keep the pond from completely freezing during winter. I read on someone else's post that during the fall, they are only running the aerator during the day and not at night. Can someone explain best practices for running an aerator at different times of year?

For context, I live in Northern Utah, so it will freeze here soon. My pond is about 40' x 85' and is about 5.5' deep in the center. Also, I've had the diffuser right in the center, but I think we want to move it closer to the edge to just keep a hole in the ice during the winter. We have some very small HBG and LMB in the pond we planted 2 or 3 months ago.

What kind of fish do you have and how big is the pond (size)? OK above I see the pond is small 40x85 = 0.07ac. Fish are HBG and LMB both fingerling sizes.
Fish species will be an important factor here. Trout require more dissolved oxygen(DO) compared to BG and LMB who need the midrange amounts of DO. Lowest DO is tolerated by yellow perch(YP) and northern pike(NP).

Two weather things will determine the condition of fish under solid ice in Utah. 1. The depth of the snow cover. 2. The length of time the snow deeper than 2" lays on the ice. Your maximum water depth of 5 ft does not allow a large storage volume/amount of dissolved oxygen in the limited or shallow depth of the pond. The deeper the pond and more water volume it has the more DO is present to last a longer period of time in the dark conditions under ice and blanket of snow. One good thing you can do to prolong the DO under complete snow cover is remove around 10% to 20% of the snow from the pond. The more snow that is removed the more DO that is created by the microalgae. This snow removal allows sunlight penetration and the microalgae makes DO to keep the fish healthy. NOTE -- cloudy muddy water reduces light penetration and thus the amount of DO production by the microalgae. Clear water will allow sunlight easily into 8ft - 10 depth of winter water. If the girls want more skating area then ask them to help remove some of the snow if you turn off the aerator. For complete snow cover and 5ft water depth, complete loss of DO which occurs from the bottom up, the adequate DO near the upper 2 ft ""should"" often last 3 weeks, although this depends on the amount of dead organic materials on the bottom. More organics cause faster depletion of DO without ice penetrating sunlight.

The other item that I have discovered with this that has an influence here. You have been running the aerator while the 6" of ice has developed. This has chilled the pond water lower than the normal winter water temp of 39F with ice cover and no aeration. Your pond water should now be around 33F to 35F compared to the 'normal' 39F. Your fish could easily be in 33F-34F water, thus they are 5F to 6 F colder. Everything in this colder water including all the decomposing bacteria will be consuming measurably less DO because it is ALL colder. Also the fish at these lower temperatures will tolerate lower DO before they die due to lower metabolism. Metabolism requires DO. Also small young fish tolerate lower DO than large fish. Old big fish require the most/highest DO. Also it is a new pond with very little organics accumulation - DO will last a lot longer due to low decay volume. So with these four items your DO should last longer before dangerous fish killing concentrations occur; up to 4 weeks, "maybe'' 5 weeks, ""maybe"" 6-7 weeks with complete snow cover. Before then and when the girls have had enough ice skating, you could restart the aerator and open an ice free hole to allow sunlight back into the pond or just keep removing snow for ice skating.

Good luck with this. Please return and up date us on the developments.

Oxygen levels in iced-over water should remain sufficient for fish IF the ice is clear to allow sunlight through for aquatic plants/algae. There's minimal plant O2 production in cold water, but also minimal O2 consumption by fish. It balances.

If the ice is cloudy or snow covered, opening a hole through the ice (or removing at least 10% of the snow cover, which has never appealed to me personally) is warranted.

Here are some ideas.
Many folks cease aeration when water temp drops in the fall. 50s is a ballpark figure. Then they resume as, or after ice is forming.
At this point, it is advisable to have the aerator in shallower water, both to allow a 39 degree warmer water refuge to develop at the deepest part of the pond, and to have some open water right at the shoreline. This second point is one of safety. A wild animal, pet, or human that falls into the open water can then make it to shore without climbing on to the ice surface.
I spent many years in northern Utah during the 60s, 70s, and 80s. Logan, SLC, Kamas. Where are you?

It a pond that size you might have water movement throughout the entire body of water no matter where you put the diffuser. There's a guy in Minnesota that runs his aeration right through the entire winter and his LMB do very well. Maybe it's because they are used to those conditions?? I don't know - I am not an expert. But I have been told on here many times that the science of winter aeration is far from complete. Please post what you end up doing and then post some updates and results as well. Not many folks with frozen over ponds posting this kind of info.

Thanks! This is great info to consider!

4CornersPuddle, I live in Box Elder County just North of Brigham City. I graduated from USU in Logan in 2006.

So I just moved the aerator closer to the edge about 2-3 feet deep. I may want to move it closer to the edge though to be sure the open water meets the shoreline. I just checked the temperature and it's not down to 50 yet. I'm thinking I may just shut the aerator off until ice starts forming. It's good to know that the diffuser may still mix things up. I've been nervous about low dissolved O2 because I dont fully understand it.

The pond was just dug in April, so the first Winter will be interesting. I'll keep you posted.

Let me know if anyone else has ideas or suggestions.

I can chime in on winter-aeration for you, from Wisconsin.
Some history from previous owner, without aeration, revealed that during the spring thaw, sometimes it appeared that "all the fish died" in 1.2 acre pond.

On my 4th winter now, all with aeration, spring thaw walk arounds show a just couple small BG total lost each year. Guessing those somehow got caught in the ice shallows.

First year, 2 diffusers 24-7 in the deepest parts (11 feet). The open water on the far end of pond got attention of some Otters. Added BG, YP and young LMB in spring.

Second year, 2 diffusers 24-7, shutdown Otter favorite far end diffuser and ran two nearer to house in 7 feet.

Third year, same as second year.

Each year, probably some "supercooling" happened, we get some stretches well below zero, but all the fish were quite healthy in spring. By the 3rd year had to heavily cull LMB population as it was exploding and BG were getting scarce. The stocked YP are getting big, not sure they have multiplied though.