Pond Boss Forums AERATION Systems questions How big is your ice hole?

Ah, northern brothers who know what it's like to have real ice. I've got a 5 CFM pump but I only run it two 4 hours shifts per day, 8 hours total. My hole always freezes over when it gets below zero. When the temperature is in the 20'sF my hole will stay about 5 feet diameter. With temps in the 30's during the day it will open up to 10 to 15 feet. I generally do not have a problem when it freezes over because the air usually finds a way out. Some times it works it's way all the way to shore and comes out under the snow. On rare occasions it will not find a way out and then it can literally build up pressure. I can see my pressure gauges go up. The back pressure in my system is normally about 8 psi. If the air gets trapped under the ice the pressure has increased to as high as 12 to 13 psi. That's when you are literally lifting up the ice. I personally think this is the only problem you have to worry about is exceeding the pressure of your pump. I use a vane pump which is only designed for 15 psi max. Hopefully you have a relief valve on your system that will trip before you overheat your pump. I have had both the tall frozen foam chimney in my pond and the trapped air that blows a guyser when it vents. Just because of the pressure increase I will usually break the ice whenever I see it frozen over with no obvious point of escape. I simply take a 22 rifle and shoot a hole in the ice from shore. I rarely have more than 1 to 3 inches of ice over the hole. Something to consider is that maybe it's a good thing to have a bunch of air trapped under the ice. If you think about it, it exposes a larger portion of the surface of the pond to air with some oxygen in it. This can only help the diffusion of oxygen into the water I would think.
Funny story - once when I had the aerator off for a few days in December as the pond first froze over, about 3 inches of ice, very clear good ice, then I turned the aerator back on. I thought it would be interesting to watch how long it took the aerator to melt a hole in 3 inches of good ice. I waited all day. The aerator never melted a hole in the ice it instead just pumped air under the ice. The pressure gauge went up to 13 psi. The ice lifted up off the water. By late that night I had a 100 foot diamter bubble of ice that had raised the ice up about 2 feet in the center. I kept watching and my ice balloon just never broke. At about midnight I was tired of waiting so I got my 22 and shot out into the center. What resulted was a huge explosion. Apparently the ice was so tight that it literally blew up. My house is about 100 feet from the pond and my family said they heard the boom. When the ice bubble burst it shattered into a million pieces. The ice chunks flew 50 feet out of the pond. I was standing on my dock which sticks out about 12 feet from shore. I was soaking wet. My wife ran out of the house wondering what happened. I simply told her that I blew up the pond! It was cool, before I shot it I thought about taking a video but my camera had recently quit working so I had no way to film it. I swear it's a true story though.