Aeration is important to a body of water for several reasons. Ideally aeration will mix the upper and lower portions of a body of water. This will break the thermocline and allow oxygen lacking water on the bottom of the lake to mix with oxygen rich water at the surface. A bottom based aerator does this most efficiently. With this type of aeration a diffuser is located on the bottom of the lake and an air pump is located on the shore. An airline carries the air from the pump to the diffuser. This can also be accomplished with wind powered aerators where the windmill is used as a pump and pushes air through the airline to the diffuser.