This is the first year for our pond. Do we need to shut the pumps down and remove them for the winter? Our pond is 2 1/2 feet at it's deepest. We will be using a di-icer. We have two bio filters that run onto waterfalls. I have heard that keeping the pumps running brings the warm water from the bottom and makes the water too cold for the fish. Is this true? Is it possible for the pumps to freeze? We live in Colorado and it gets pretty cold in the winter. And if we do take the pumps out, do they have too stay wet to keep from drying the gaskets out? Any advice will be greatly appreciated. Thanks!