We have a 27 foot above ground pool. I have used the cover and expandable plugs successfully for years. I keep my pool here in Virginia full and usually have to purchase one load of water in the Spring because, I believe the ice/snow on top pushes some water out. Unrelated, but thanks to Ben for saving us so much with the "chemicals". It really "burns" the pool stores when you tell them you use clorox and most everything else you need from the grocery store. Don't forget the poly! Have a great day.