My installers instructed me not to fill the pool overnight due to the cold night air is making the liner shrink and the water is making the liner stretch - made sense and I turned off the water at night. It took at least 2 full days to fill that thing. As far as water temps - the water out of the hose today was about 59º. I had the pool installed about the same time 5 years ago so I would imagine it was about the same temp.