Hi I am new to this site. I have a 12x24 oval, 7,400 gal AG, 1.5 hp Pentair filter system with Nature 2 system. This set up is meant to be low chlorine. My problem is no FC. My TC is 4.2 ppm. I asked my pool guy about using household bleach to try and "unlock" the CC and he said that household bleach is bad for the vinyl liner. Is there any truth to this or he is trying to keep my buy his chemicals? Any other ideas to raise my FC and lower my TC levels?