I have a combination of factors that make me think that I may be better off not lowering my water level for the winter. I have a Pebblesheen pool with a sun shelf that's about 15" deep. When closing my pool last year, I lowered my water level down below my returns which put the water level at about even with the surface of the sun shelf. Due to do the shape of my pool, a raised spa, and a raised wall, we do not cover our pool. Throughout the winter my water level rose a little with rain and snow. From time to time, I would pump it back down with a submersible pump. When we opened our pool this spring, we noticed that there were quarter-sized spots on the sun shelf where the Pebblesheen was flaking off. We went a few rounds with both our PebbleTech installer (who seemed to be playing dumb) and PebbleTech corporate. In the end, PebbleTech concluded that the flaking was caused by freeze damage which they repaired. Apparently, a small amount of water penetrates the surface of the Pebblesheen. When the water freezes, it expands and loosens the surface of the plaster. Even if I kept the water level below the sun shelf, rain and snow could also freeze on the surface. PebbleTech's answer was to cover the sun shelf with plastic. I think it is going to be near impossible to keep water off the sun shelf all winter. Also, if I keep my water below my sun shelf, it will cost me about $500 to fill it back up every spring.
I'm thinking about solving this in the other direction. If I keep my pool full all winter, I think it's going to take one heck of a freeze to get a layer of ice down 15-18 inches to freeze the surface of the sun shelf. What are the risks in not lowering my water? I have tile around the waterline. Do you think the surface ice likely damage the pool tile? I'll have the skimmers protected with an antifreeze bottle, so I don't think I'm at risk of cracking my skimmer.
You advice is greatly appreciated. I haven't been able to figure out the right answer so I haven't closed my pool yet. Tonight, it's dropping below freezing so I need to do something soon.