I'm not going to make assumptions without data. You know what assume means, and during the last 2 years I have been doing some testing here as well because I don't like to assume. The testing has been done in a small pond compared to yours and a lake that is 36x larger than your pond. While we don't have the same thickness of ice, we DO get ice and I can't believe that you can form more ice in the time that the system is off than we can if the system here is off for the same amount of time with relatively close to the same ambient temperature. After all, you are not trying to burn a hole through 3' of ice, you are trying to go through ice that has formed since the time the system has been off. Our ambient air temps would be pretty close too, we will see temps from +30°F to -20°F and I can pick ambient temp to start and stop the system here. I have done some testing here as well when the ice first formed and was between 1" and 2" thick and there was no snow on it. It was very easy to watch the air coming up to the ice from the diffusers and what happened to that air.

Until the data comes back in I will just do as Brian suggested and shut up. As a moderator I know it takes 2 and I won't go there. I would like to know how many CFM each compressor that you have is pushing to the pond, and to what "hole" in the pond ice it's pushing that air to; i.e., How much CFM do you have feeding each of the ones (1,2,3?) Or are all of them fed off of the same compressor? If so, what cfm is that output at your elevation? I know how much the Koenders windmills push, there are 2 of them here feeding two different ponds at a customers place, along with a Koenders electric compressor feeding a 3rd pond. Are you using a Vertex diffuser with the Koenders system or the one that came from them?

Here is what I'd like to know, plus the temp and O2 profile once the data is available. I have assumptions on what that is, but want to know for sure.

1) You have the close dual. What water depth is that placed at and how many cfm (if known)?

2) You have the quad. What water depth is that placed at and how many cfm (if known)?

3) You have the one with the pipe. How many diffusers and what depth of water is that placed at and how many cfm (if known)?

4) Then there is the Koenders. What depth of water is that placed at?

Are you running Vertex diffusers at all of the places (1,2, and 3)?
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).