Its really up to you. I live in northern NJ and my IG pool is about 29,000 gallons. It was 45 degrees when I opened it at the beginning of the month. I turned the heatpump on last Thursday and was swimming in 72 degree water on Saturday. I will not heat it up to 78-80 until mid-May, but until then I will keep it between 70-72 degrees. Remember that the ground temperature is not going to change that much. As long as you keep the solar cover on when not in use you won't loose that much more now than in a month or so.
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