High Heater Operating Costs

        Keep in mind that in the middle of the winter, without a good pool cover, with a standard Natural Gas heater, it can cost well over $1000 a month, probably closer to $2000. Propane can cost many times more, provided you have enough propane in the first place.
            Getting a good pool cover will greatly decrease these costs, i.e. by slightly more than half. Also, just adding a good cover will add about one month to the beginning of your swim season, and about the same to the end of it.
            Want to save even more, get a heat pump. It can make your pool swimmable (with a good cover) for most of the time when most people can "tolerate" being wet, and being outside in the open air. (In other words, if you couldn't stand being wet in 40 degree weather, you aren't going to be comfortable in the pool either. The total cost with a good cover, and a good heat pump, is around $3-$4 a day.