We have a 21×42 AGP that lost 2/3 of its water last winter. We hired a pool service firm to open it then and tell us where it was leaking and if it needed a liner (we'd probably remove it, instead as the kid is grown). He told us that the liner was fine, but our old cover was letting water leak above the cover and evaporate. He also said that we should change from using three separate pillows (4 ft) to one 16 ftx4 ft pillow (one of our 4 ft pillows had deflated).
The pool was open all summer and the water level behavior was normal. We had the pool service firm close the pool using a single large pillow and new cover supplied by them. All was well until this month. Water level was steady. We could drain water regularly (although we never get it all off). This month the weather got colder and snowier, and we haven't been able to drain the cover. In addition, the large pillow shifted from the center of the pool to one side along the pool wall.
When we looked out yesterday morning (after not checking for a week or so, the water level was down 2 ft. The cover is stretched to its limit. We broke through the ice and are draining what we can.
Water level originally was below the Skimmer. Skimmer and return were blocked. No other openings to pool.
What could cause this behavior, and what can I do to correct it? Should I try to add water under the cover? The pool service firm has not responded to our messages.
Thanks in advance for your help.