I am considering installation of a Jandy 400,000 BTU NG pool heater to heat my new 25x45 37,000 gallon in-ground pool. I did some rough calcs and came up with about 1 hour to raise pool temperature 1 degree F. Does that sound right? And can one simply extrapolate to get 10 degree increase in 10 hours? Also how much does heat loss to ambient impact time to heat pool? Thanks for any info.