Here are 4 pictures from today, 1-22-2020 Daytime temp 30°F, night time temp 26°F. Diffuser in shallow water directly under the pier is in 14" water depth, diffusers at each side of the pier at the end is in 26" water depth. (added depth measurements)

3 Vertex fine bubble diffusers compressor is producing 2 cfm. System running 24/7.

That's a public or shared pond / lake? Maybe for safety sake post some signs for open water? I'd hate to see someone break through thin ice while walking or snowmobiling. Just a thought.

Public lake. If someone goes into the water, then they will be wet and cold, but they can walk out - water depth is less than 48" at the deepest point of any thin ice, less where the water is actually not frozen.

Update:

Using the bigger compressor, and pushing approximately 3 cfm through each membrane diffuser (instead of 0.75 cfm) opened the holes up to 19 feet radius. The pier is completely ice free now, With the warmer temps I swapped back to the smaller compressor on Monday and will measure the amount of open water on Friday.

I now have medium and coarse bubble size membrane diffusers to put in the system, and will continue testing. In approximately 10 days, we will see colder weather, highs in the low to mid 20's, lows in the single digits/teens overnight.

Unfortunately the medium bubble size diffusers are rated at 1.5-10 cfm, the coarse ones 2.0-12 cfm. So they may not work with the small compressor....... They will be tested anyway with both compressors.

Water is shallower than I thought, under the pier where the diffuser is closest to shore the water depth is 14", near end of pier where the deeper diffusers are placed the water depth is 26".

I had turned the aeration system off in my pond on Sunday, the open water has frozen back closed. On Friday I will turn the system back on and see what happens to the air under the ice, there is a spot of relatively clear ice approximately 80 feet in diameter, so I can watch what the air does.

Have you thought of trying a run of soaker hose around the entire dock as a loop? I have seen this done in a few places, not sure how big a pump on it, but seems to keep the dock area open. trial and error are good teachers.

Esshup - sidetrack a little bit - is that a particular Brand of dock you have here? Looks like some online that I have been researching for a pond dock. Need something simple like this.

Thanks for the info Scott. Looking forward to more. What brand of membranes are you using for the coarse bubbles?

I'll ask my client, it's his pier. We have a house 5 houses to the right of the pier, directly across the lake and we don't have any problems with ice. His pier has large plastic wheels at the deep end.

Atlantic brand; first time using them. They are cheap. I would NOT consider using them if I was going to run them any other time of the year besides winter for de-icing the pond. I can't find any information on lifting rates, and from their CFM specifications I believe they are designed to be used with a high volume compressor or even possibly a high volume regenerative blower.

That is the last thing I'm going to try, one like this: Pentair AES Regenerative Blower 1/3 hp

27 CFM @ 20", 19 cfm @ 30" I'd have to swap out the air line too, this requires a 1" airline.