I am heating my pool for the first time for a kid's party tomorrow. I have a 32'x15 (approx. 15K Gallons) in-ground, free form pool with an attached spa (9'x7' oval - approx 50 sq ft). The spa is elevated 18" with the typical 2' waterfall into the pool. I have a 400K LP Heater. The current pool temp is 72 since it has been raining for 2 days. The air temp should hit 78 today with some clouds. Going down to 55 tonight. The whole pool is screened in, so that would help with any wind. The party is at 2pm tomorrow. I figured I would start the heater today around 1pm and monitor for 5 hours to see what type of increase I get. Then I can leave the heater on overnight or wake up early and start again. I do not have a solar blanket.
I'm hoping you can help with the questions:
1. Should I isolate the pool from the spa and just heat the pool? Or should I heat it in regular pool mode and have the hot water enter the pool and spa, utilizing the waterfall? I also have two foam jets that i think I should keep off.
2. I did all the calculations and it looks like it should take 6 hours. This seems a little low to me. I did the calculations on 16,000 Gallons.
3. Any calculations on how much the temp would drop overnight without a blanket? I've read I could lose up to 50% of the increase.