Hi All, just curious about something. My DO was about 7 to 8ppm at ice up in late november, tested last week at about 2 to 3ppm 2 feet below the surface. Newly made 6 acre lake with very little vegetation to decompose. Ice thickness is about 16 to 18 inches, there is good light penetration and I see blooms of plankton and lots of copepods and little things swimming around in front of the camera. So my question is that now with the longer days and more light penetration should I see an increase in DO? There isnt a large demand on the DO from what I can tell but it has dropped according to my old test kit (if its still accurate). Im hoping what fish i have in there to date wont winterkill.
From pics your fish are active. How deep was the picture taken? I think the fish in 39F water can survive on 2ppm DO. How much snow cover is on the ice and is top layer of ice clear or milky? Clear ice should allow enough light to the water with plankton below clear ice to make 2ppm DO per sunny day. Check the accuracy of the DO tester. Check your tester. The DO in some water that you know has good DO such as a sample from open surface water shaken in a jar for fresh from a stream. That DO should be at least 8 - 10 ppm or higher.
Your water appears to be stained very dark brown in the last photo.
What is your source of water? If it is surface water coming through a forest, there may be a fair bit of tiny particles of organic matter coming into your pond. Those will decompose over the winter and consume some oxygen.
It is true that the plants in the pond that die during the winter will decompose and consume some oxygen. However, the plants that survive and get some sunlight through the ice will be suppliers of oxygen. Hopefully, you can get some beneficial plants established this year.
Keep making the holes in your ice cover, that can only help!
Yes it has lots of tannins in it from when we filled it from the upper swamps in the summer, Im hoping it will flush out this spring/summer. Previously the water was very clear with no tannins.
Trout staying higher in the water column indicates lower DO than 5ppm deeper. Tannin stained water does reduce sunlight penetration and less natural DO production. The thick layer of cloudy ice inhibits sunlight penetration and DO production. Small area of open water with diffuser action should help add some DO but not a lot. Apparently the fish have found the diffuser boil area with water having some higher DO. If you did not have the diffuser operating I think there would be a noticeable fish winter kill. IMO if you can keep an aeration diffuser area ice free the trout should survive this winter.
