Let me clarify. During the winter you're not getting any real aeration from the bubbles. One of the main reasons for the aerator in the winter is to keep a hole open in the ice. You have a better chance where the air has less resistance during the up flow. It betters your chance of the aerator keeping a hole open in the ice...more surface agitation.
Another reason for raising the air stones is that when set low, you pull the warmer water from the bottom and mix it with colder water nearer the surface. The idea is to keep as much warmth as you can where the fish hang out. Experiences of some of the seasoned vets on this other forum say the chances for a greater fish kill during winter months happens when the aerators are placed low in the water.
