In the spirit of sharing our knowledge, I'd like to share my observations for those that are building a pool now or considering what equipment/products to use for their pool.
Our pool is a 42,000 gallon, inground and it is new. We finished it late in the fall, and filled it with water May 31st. We installed a heat pump, but it has been broken from the beginning. Yesterday, the company finally installed a new one. So, until yesterday we've had nothing to heat the pool with other than the suns rays. We do get 12 hours of direct sunlight on the pool, and it is not very windy where we live in NorthEast Ohio.
From the day we filled it, we have been very diligent about keeping our clear 12 mil solar cover on. Our pool took about 10 days to warm up to 75-80 degrees, and not much longer to be 82 or higher every day. We feel this is a comfortable swimming temperature where we can stay in the pool for hours. I notice that we typically lose 3-4 degrees overnight, and gain it all back every day.
This has been the coldest summer I can remember, and our nights have been in the 50's, whereas typically this time of year it might still be above 80 degrees air temp at night.
My conclusion- I wish I would not have bought a $3500 heat pump, nor paid to have it wired and installed. It seems I'm going to heat the water up 5 days quicker at the beginning of the swim season, and that is about all I will gain. It seems that even with this mild summer the water temp has been perfect, and using the solar cover with the roller has been pretty easy.
I hope someone can learn from my experience.