Fyfer - My pond is making more ice today because the ice is expanding upward and cracking. Ice yesterday was 3" thick as I walked on it.
Okay your pond has and maintains trout. That makes water quality and dissolved oxygen more important during ice cover. Trout as cold blooded critters do not require quite as much DO when water is 39F as they do when water is 60F-65F (5ppm) because their body metabolism is measurably less in 39F water compared to 65F water. The body metabolism is what consumes and requires the DO. Faster is more; less is less.
Measureable amounts of muck and leaves on the bottom speeds the loss of dissolved oxygen (DO) from water when 2" or more of snow covers the ice. Snow on ice significantly inhibits light penetration. Deeper snow eliminates light penetration. Light penetration stimulates phytoplankton to make DO under the ice IF and IF the phytoplankton receives sunlight through the ice.
If you want ice for skating, this is what I would do and still have a 95% chance of overwintering trout in the features of your specific pond.
Move the aerator into 3 to 5 ft of water for emergency aeration. Or leave it where it is. There should be a slow slope to sit the aerator or just let it hang along an almost vertical wall in 3-4ft of water.
Turn off the aerator.
Let the water freeze and when ice is safe to walk on 4"+ shovel or 6"+ snow blow off snow whenever it gets deeper than 3"(7cm). Remove enough snow for some ice skating area and this should be enough surface area to get enough light through the ice and into the water to allow phytoplankton to make DO to maintain the trout. The more snow that you can remove the better especially if the ice is cloudy on top. Usually cloudy top ice has glass clear ice below it. Water with 6-8ft of visibility still has lots of microscopic phytoplankton (tens of thousands per ounce of water) for winter DO production. Water with this amount of phytoplankton in 6ft+ clarity does not have significantly high plankton densities to cause rapid DO loss under snow covered ice. DO loss in dark does occur but not faster than several weeks. Your 14ft ave depth extends this time.
If the wind can blow snow off large areas of the pond then snow removal is not necessary. This is why frozen SHALLOW ponds exposed to strong winds and snow is regularly blown off rarely have winter fish kills. In my area we regularly have January or a February thaw and a noticalbe snow melt. This gets light back into the pond so the phytoplankton can again make and restore the DO.
Normally I like to get a pond surface area of 10% snow removed and for your 1 ac this is an area of around 65x65ft - around 4300 sqft. In small lakes snow is removed in alternating strips so sunlight penetrates the length of the lake or large pond.
Wood our Canada PB member in Manitoba or Saskatchewan had trout in his smaller, shallower pond than yours. Deep water holds more volume of DO compared to shallower 6-10ft of water. We educated him and he consistently and regularly shoveled snow off the ice that was a whopping 3 ft thick. This snow removal allowed light to penetrate through the 3 ft of ice for the phytoplankton to make DO to keep the trout alive. Wood sold the property so he regretfully is no longer is a PB member. Maybe I can find a link to his PB threads about his pond and snow removal success story.
In a pond such as yours with ave depth of 14ft containing trout and clear water, snow does not need to be removed until snow of 3"+ lies on the ice for longer than 4 weeks. Now at this point DO starts to be slowly or gradually lost from the bottom towards the top. Length of time until the DO is lost at just under the ice through 14 ft can take a few more weeks. However since you have trout be concerned when a snow blanket lays on your pond longer than 4 weeks.
Then at 4 weeks or more conservatively 3 weeks, ,,, START your aerator that has the diffuser in 3ft of water and let it run until it opens a hole 6ft-10ft dia or more in the ice. Turn off the aerator. Thereafter then run the aerator each day just long enough to reopen the 6-10ft dia hole.
Thank you for the very detailed reply. We do get a lot of snow and very cloudy ice due to the fact that cold temperatures here almost always result in lake effect snow from Georgian Bay (Lake Huron). However, we always keep a shoveled area about as large as you mentioned for skating. I also keep some other areas shoveled so I can walk and fish. We have had one small fish kill after ice out a couple of winters ago but the pond generally seems to support trout all year round. Some trout have been there almost 5 years.
In regards to the aerator, is there is problem turning it on now or in a few days? I have not had a chance to check, but I'm almost sure that the area that it kept open is frozen over and safe to walk on now. Additionally, it is currently at the bottom in 14ft of water because we have no shallow areas of the pond. The walls are straight drop offs. What is the benefit of making it hand midway down the water column?
Thanks again.
