I have a 38ft * 15ft rectangular pool and the largest solar cover I could get was 35ft long so I had for a while a gap at the end of the pool. It still saved a heap of water evaporation and heated the pool by 9F. I found the biggest things with the solar cover was the ease of getting it on and off. In my first season with the pool cover I was too particular about keeping it on correctly and so less time was spent in the pool cos' it was a hassle, so it has to be easy and quick. The cover can be a bit heavy to roll up and get kinks in it so if you have odd shaped bits, I would only use them in the off season to protect your pool. If it takes the kids only 30 secs to roll it up and dive in, they will use it. Hope this helps.