Ron,
Will you keep your fountain running Tuesday night, or shut it off some time Monday?

Thanks for the very good explaination Ron. It now makes sense to me.

My waterfalls shuts off every night around 11 pm. along with the flood lights, and all of the water drains back into the ground. So there is know worry about freeze damage, and the water stays above freezing because it is down in the ground. As far as Gracie's question, leave your fountain run that's about the best thing you can do. If you want you can purchase a heating element that keeps the water from freezing, and put that in the fountain and plug it in during freezing weather.