Would like to add a heater to my pool to extend my season. Help get it up to temp quicker in may and keep it decent through the end of sept. We have days in the 80s through early oct thats nice enough to swim but 75 deg water is a little cold to enjoy Not planning on running it to stay at 90 around the clock just be able to get it into the low 80s where its comfortable if we wanna swim that evening. Whats typical cost per degree in a 16k pool on propane?