The purpose of aerators and bubblers is to keep water from freezing around pier legs, thereby preventing damage and allowing piers to remain in the water over the winter.

But do they work? The short answer is no.

To be sure, they do keep the water from freezing around the legs. But the most significant threat to a pier comes in the spring, and it comes in a way that pretty much laughs at the small unfrozen areas around an aerated dock. As explained on our “Ice behaviors” page:

During the spring thaw, the ice sheet starts melting from the shore first and proceeds toward the center. For varying periods of time each spring, the entire ice sheet is a big, pancake-shaped free-floating iceberg, literally.

It’s at this point that the ice is dangerous to any structures in or near the shoreline. Wind blowing across the lake will push this iceberg against the downwind shore. The stronger the wind, the more forcefully the ice sheet will push against shore. If the wind is strong enough, the ice will break up at the point of contact and pile up on shore. The process will continue until a broad enough area of contact develops to hold back the ice flow.

With a strong enough wind or a large enough ice sheet, the ice may just continue flowing regardless – until too little ice sheet is left to catch the wind or the wind subsides. Obviously the larger the lake, the more dangerous the flow. With the right conditions, the forces on the shore or its structures can be enough to move car-sized boulders, let alone piers.

The rule of thumb for pier owners is: sooner or later you will get a strong wind during those critical few weeks of spring and if you leave your pier in over the winter, sooner or later it will be destroyed or taken out to sea. The larger your lake, the worse your chances. For a pond you needn’t worry. For Lake Superior you’ll lose your pier, period.

A little notch carved out of the ice sheet by an aerator or bubbler will be ignored by a moving sheet of ice. Any ice sheet that is moving fast enough and driving hard enough to cause damage is moving hundreds to thousands of times too fast for aerators or bubblers to be able to melt before damage is caused.

You are no more or no less vulnerable to losing your pier from ice with or without ice melters. Statistically, the chances any given pier might be damaged this way may be very small on any particular lake, and this may lull one into some confidence that an ice melter is working. Make no mistake, it’s just luck.

The Wisconsin DNR goes into more detail on how to avoid ice damage here.