Karin, you mentioned you might use a metal sequesterant. I have used Jack's Purple Stuff which is good stuff except I have verified now that is has phosphonic acid which is probably why I continuously have high phosphates (been using the stuff weekly since March). I will cease using it today. Natural Chemistry has some stuff called "Metal Free", I think, and it is phosphate free per the bottle label. Good luck and listen to Waterbear.

Mike