Hi Dave, I am still trying to figure out what causes the stains. Your numbers seem perfect to me. Have you added any sequestering agent since opening? I also read somewhere that "Fiberglass has a negative electrical charge and can attract positively charged metallic ions, causing the development of a stain. The periodic addition of a metal treatment should help negate this effect and help keep pool stain free. " I don't know if any of this is true - but it would seem to be a reason that the fiberglass stains so easily. I haven't opened my pool yet this year, probably in about 3 weeks. I plan to add sequasol first before anything, then test all the chems and bring up the chlorine slowly. I think the most important is to have the sequestering agent in the water in a large quantity before doing anything at all, including a stain treatment. Maybe between all of us we can figure out why we get the stains - we know how to get rid of them, but it would be nice to not ever get them!