We haven't had a cold enough winter for me to get valid test results, BUT from initial testing using fine bubbles and .65 CFM per Vertex diffuser vs 3.3 CFM thru each diffuser showed change in the hole opened from 3'-4' diameter to roughly 15'-18' diameter.

That is with the diffusers placed at 2 feet below the ice.

In another pond where the diffuser has medium sized bubbles and is running about 6 CFM, and placed roughly 5'-6' below the ice, the hole is approximately 40' in diameter.

I wanted to do a test this winter by leaving the diffuser depth unchanged but swapping to different sized bubbles while keeping the CFM the same but the weather didn't cooperate. Our ponds and the majority of the lakes here were ice free 3-2-2020.

I think your biggest problem is having the diffusers placed too far away from the water surface (ice) during the winter, allowing the whole water column to super cool. Think about it for a minute, if you wanted to melt ice, would you rather use 33°F water or 35°F-36°F water?


3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).