Sorry if this has already been discussed ad nauseum, but I couldn't seem to find anything on it. I am very interested in putting in rain barrels for water collection. The problem I foresee is that I live in an area of the country that is prone to below freezing temperature during the winter and I have concerns that the water will freeze from time to time meaning A) I won't be able to use it and B) my water collection container may crack. Does anyone have experience with this? Are there small circulator pumps that folks use to prevent this (or other means)?