I've read over and over ---- Bleach is Bleach --- Chlorine is Chlorine and I accept most of that.

This is NOT an new pool --- We have had this pool 4 years and used Cal Hypo since it was new --- NO STAIN --- 2 weeks into usiing Sodium Hypochlorite and we have stains ---- There has to be a correlation to the reaction or chemical composition of the Sodium Hypochlorite ----- and a preventative measure.

I'm really more concerned with that aspect than I am with the stain which is why I posted to this forum instead of stains etc.

EDIT: Also the pH has been stable with no muriatic being necessary