Mark,

This thread has become as convoluted as any post I've seen lately. I'm going to drop out with these thoughts.

I don't think it has been determined that acid will not harm your fibreglas. It probably won't, but nothing in this thread promises that.

Secondly, I would be very careful draining that pool. Fibreglas pools are designed to be kept full and draining one would, IMHO, jeopardize the structural integrity of your pool.

Dave S.