The pool is absolutley perfect, crystal clear !! What is interesting is that I had a green "stain" about 12 x 12 inches on the liner in the deepest part of the pool. I know that's where the leaves that were in the pool when it was closed last year. I thought the liner was stained from the leaves themselves , but now after all the LC and Calcium hypo shock. It is gone. I'm assuming it was some kind of mildew or mold on the liner that was eating up all the FCL ? How do I prevent this in the future ??