[MotoSook]

Give you a real world example, we have a 28,000+ gallon inground pool. To heat it from 60F to 85F and maintain 85F for a month, it probably cost me $300-$400 from Thanksgiving through Christmas when the kids were off school.

You will have losses during your ramp up from 50 to 80 degrees. Your water probably comes out of the faucet at 50 degrees during the spring. So assuming 50 to 80 is fair. It's about 314,000 Btu/10F to heat the water in an ideal world.

Your pool is about 1/10th of my pool and you'll be heating it during a warmer ambient period...you're looking at less than $100, and more than $10. That give you the order of magnitude you looking for?