I remember that thread and was part of it. I think it was Watermom who suggested an oversize tarp could be laid across the pool and new water added to it. As the rate of incoming new water and outgoing old water are kept approximately the same, the tarp would form a membrane against the sides and bottom of the existing liner due to the weight of new water.

This really sounds like a good idea to me, but when I posted a new thread asking about the experiences of anyone who might have had success with this approach, I got no response -- either positive or negative.

I will probably be trying it next spring if my CYA doesn't come down over the winter (and from what I read in these forums, it most probably won't).

-Jim