I live in Maryland and have a heat pump that has worked fairly well. I have been able to swim into October (I also have a cover). Now that the temperatures, particularly at night, are dropping the heat pump is having trouble. I want to keep swimming. I was wondering about the possibility of having both a heat pump and a propane heater. I would use the heat pump most of the time, but when it starts to get too cold for the heat pump, I would use the propane heater to give the heat pump a boost. Does anyone have experience doing something like that and does that work? Thanks.