So the water will be warmer under the diffuser? I thought the pond would be turning several times throughout the day and the water would be the same temperature or close to it. So if I run my diffusers during the winter it will keep the ice off but possibly make the water too cold? I guess there is a happy medium.....leave the diffuser off in the deep end and run the diffuser on the shallower end, possibly suspended off the bottom? This will keep warmer water in the deeper part of the pond and keep the ice off the other end which will allow sunlight and oxygen in.