Here is a link to an informative newspaper article that discusses how snow cover on ice and certain related conditions can contribute to winter fish kills. The article mentions that a fish hatchery uses winter aeration in shallow water to help reduce the chance of fish kills. I am currently using and testing deep water diffuser aeration as opposed to shallow water aeration and how it will affect the water conditions under ice and snow cover.
http://www.toledoblade.com/MattMarkey/20...fish-kills.html

What about the idea of shallow water diffuser running all the time that keeps open water, along with a deep diffuser that only runs short periods and only a portion of the day (separate pump on a timer)?

From what I have read about super cooling the BOW on older threads, cooling all the water down and stressing the fish is the danger. The Earth warms the deeper water.

But what if a person only ran the deep diffuser enough to transfer only a portion of the water at a time, but not enough so it would cool off too much and the Earth would again have time to keep it warm enough.

A possibility? Would this be helpful?

Makes sense snrub but as things get more complex many people have issues tweaking things. Additionally a D.O. meter with temperature would be a must if you are taking this approach.

But your idea really has merit. After this winter I will be watching things closely with my D.O. meter and may give that a try!

Until my new rationale chances, it is better to have a deep water diffuser going and super cooling a large portion of the pond with high DO and mildly stressed live fish rather than having a small near shore area aerated and dead fish. Which way makes more sense? Fish appear to survive just fine in the super cold water in far northern streams with open water (rapids) during very cold winters. The main exception is where shad and probably prior stressed fish are present and they do not tolerate super chilled water very well. I have measured winter stream temperatures to be 33-34F.

Bill, what about ponds that have RES in them?

I'm not totally sold on the super chilling thing but definitely would rather have super chilling than low D.O.

The reason I am not sold on super chilling is I had a situation a few years ago where my D.O. levels were getting low. I cut a hole in the ice and inserted a Kasco surface aerator off the side of the pier in my big pond. Even with below zero temps it opened a hole 30 feet wide. I had fish cages in close proximity to the Kasco and never lost a fish. I mean the Kasco was right there next to the cage! (Started on the right side of the pier in the picture and moved past the cages and under the pier to where it is in the picture.)The ice did go out about a week or so later. Perhaps the stress wasn't long enough vs. an entire winter?

I've run our station of (3) 9" EDI bottom diffusers on a timer the past two winters in liue of messing with pulling it shallower and it seems to be working just fine. Currently I have it setup to run 20 min @3:30 am and another 20 min at 3:00pm. It's kept a hole 15-20 yds across or better for the majority of winter on our 2acre pond.

In 3 of the 4 ponds by me, the fish may be toast.

Only one runs a diffuser to keep the water open. The other 3 have been sealed off with snow and ice for about 2 months now.

The 3/4 acre pond out my back door, may have a spot or two that maybe gets to about 7'-8' at best.

Don't know how thick the cover is on these, but I have meats stored in a steel cabinet in my garage that have been frozen solid for the past couple months.

I am leary about winter aeration and super cooling the water due to my redear sunfish population. Thoughts on RES and winter aeration?

I did go scoop some paths on the ice tonight from yesterdays light snowfall we had.

Yes if you have RES in the pond I would only aerate with the diffusers set close to shore or in the shallow end of the pond. RES are definitely a warmer water fish. Water temps of 36-38F will likely cause kills? If Cecil had his temperature gauge at home, I would have him go and check the deep water temperatures at various locations moving away from the shallow water diffuser until he got to the other end of the pond. There is still a lot to learn about winter aeration in sport fishing ponds.

Well I wish there was some data that I could help with. In our perch pond I have run one air station in 12 feet of water 24/7 this winter and it has been so cold that twice it has frozen right over the aerator.

I have also had my pump pumping from our spring fed creek at a rate of 2500 gallons per hour over the water fall all winter too. There is a solid 6"s of ice over the water fall but the water is running under the ice down into the pond. It then runs to the other end of the pond and out the over flow.

We have a solid 24"s of good black ice over the pond and 15"s of snow now on it as well.

Last year we has some pumpkin seed cross redear sun fish and they all died. A happy misfortune. The only reason we had these fish were because I didn't know about this site and going by what the fish supplier suggested.

If there is any help I can be let me know.

Cheers Don.

Don - You can find out how your fish are doing by doing a little ice fishing. If you can catch a fish near the bottom in deep water there is adequate oxygen there. I suspect the creek water may have a good influence on the pond. Can you measure the water temp of the water entering the pond? Most of the pond is likely close to the same temperature due to a short retention time?.?

Below is the impact of using a diffuser set at 12ft deep (pond 16ft deep) under ice and snow cover. Snow cover since late December.

Back on Jan 18 pre-aeration, DO at 5ft to bottom was 2.0-2.3 ppm (mg/L); water temp was 39F and 40F at bottom.

Aeration started Jan 18th and after 4 days DO increased to 6.3Surf, middle 4.5 and bottom 3.2-3.4 ppm. Water column and bottom temps now 36.0-36.3F.

On Feb3 after aerating 16 days DO was 5.1 to 6.1 and water bottom temps dropped to 33.6-34.4F. Aeration was stopped since water had good DO although water temps were abnormally cold. I did not want to continue aerating an take a change of further decreasing water temps. My philosophy was low water temps are better for the fish compared to no or too low of dissolved oxygen. Aerator shut off Feb 08. It had been running 5 hrs per day keeping a water opening about 60ft diameter that refroze closed each night.

On Feb 11 with aerator still off 3days, ice above the aerator was 5" thick after aerator was shut off 3 days ago (Feb08) before the last 7" snow. Ice in several other areas of the pond was a pretty uniform 11" thick with 6"-10" of snow cover. DO at bottom in several areas was still good 3.6, 4.0, 4.6. Bottom temps had warmed slightly to 34.4 to 35.1 from the previous 33.4-33.6F. DO consumption was slow probably due to colder than normal winter's water temp of 39F.