I have relied on this forum for a wealth of information, including "ideal" chemical levels. And the rational behind these recommended levels certainly seems to be based on good science. Nevertheless, I cannot help but wonder why there is such a divergence from these "ideal" levels as recommended by industry stalwarts such as Pentair & the National Plaster Council (e.g. calcium hardness & total alkalinity) I can only assume that these entities rely on similar science. Admittedly, however, there is certainly some overlap with all of these recommendations. Your thoughts? Thank you.