Before I ask my question let me say that I read this forum all the time and find it an invaluable source of knowledge. I used the advice found here to convert my pool to the BBB method a couple of years ago and love it!
First some background info about the two pools in my question.
I have a 24 foot above ground pool, no heater, North Georgia, still covered for winter, water at 56 degrees.
My sister-in-law lives three blocks away. Her pool is 28 feet above ground, SWG, no heater, not covered for winter, pump ran all winter, water at 70 degrees!
My question is, why is her water so much warmer than mine? I have always heard that a covered pool warms up faster than an uncovered pool. But that isn't the case here.
I have two theories as to the temp difference.
1. Running the pump and the SWG creates a lot more heat than I would have thought. Or
2. My cover has a 12 to 18 inch air gap between the cover and the water, as I try to keep the cover as tight as I can. Maybe this air gap is preventing the water from absorbing as much heat as her pool is absorbing.
It sounds like I should remove the cover and open the pool.