I need a little bit of help understanding my SWG. I have a auto pilot nano. When it shows petrified % what does that mean? It defaults to 50%. The nano is showing 3100 ppm but when I check the chlorine levels when it is reunning the pool shows high but when I turn it off for 10 or so hours and check it again it show almost no chlorine levels. I have read that manual over two or three time and it dose not make since to me. If someone could give me a basic understanding of this device I would appreciate it.