Kasco Robust-Aire bottom air diffusers provide increased water circulation and the addition of oxygen to the bottom of a lake. These units are typically used in lakes with depths exceeding 8 feet. In the heat of summer, lakes with greater depths are at a higher risk of stratification. By placing bottom air diffusers, you create an updraft of water that helps to circulate the entire lake and reduce stratification. This ultimately reduces the risk of lake turnovers that could cause fish kills.