Do you need to run your pump 16 hours each day to prevent freezing ? I am on a demand type plan as well. 9pm to 9am and weekends is the cheap time. In the winter I only run my pump for 4.5 hours (9pm - 1:30am) and as the summer arrives and the water temp increases I add a second run in the early morning. By June or so I'm running the pump 4 hours at night and 4 hours in the morning max. This systems works best for my pool, provides plenty of time to keep it clean and generate chlorine.