I have a 4 year old 16k concrete pool with a tile waterline we've opened and closed every year with no problems.
I was trying to think of a way to leave the water level up this time by putting some kind of expansion protection in the pool just like the foam water tubes we put in the skimmers to protect the tile from ice freeze. I would also use some sealing skimmer doors to help keep them dry. Anyone done this? I'm in OKC and it gets in the 20's every winter so I need to protect the tile, I wonder if one of those cover support balls would contract with freezing...or some bigger tubes anchored to the bottom? My plaster looks nasty at the lowered waterline for months every year and I'd rather keep that nastiness on the tile!