I have to report that I added Jacks Magic Magenta stuff as per directions, the spots got worse for the next few days and I stuck to my BBB chemestries and after a week it is essentially spot free. In conclusion I believe they were copper and probably iron stains to some extent that precipitated during the spring when the pollen fell and the pH was relatively high. I suppose they r now in solution and the metals are gradually being removed by the filter. I am not sure for how long to use the chelator (I have been adding 8 ounces per week). I will soon start using boric acid and once again your web site is fantastic.