We have a catalytic carbon + water softener system, running for 4 years now. Over the last year or two the master bathroom toilet has slowly developed this blackish/gray staining in just the bottom of the bowl, and now the other two toilets in the house are slowly developing the stain. Scrubbing with toilet bowl cleaner and a pumice stick does nothing to remove it. I thought water softeners were supposed to keep toilets nice and white? I have a Hach 5B test kit and test every month, the result is always 0-1 drops of solution to turn the test water from pink to blue.
Any ideas? I've enclosed three pictures one of each toilet with the varying degree of black/gray staining.
Guest bathroom toilet upstairs:
Master bathroom upstairs:
Downstairs toilet:
Any ideas? I've enclosed three pictures one of each toilet with the varying degree of black/gray staining.
Guest bathroom toilet upstairs:
Master bathroom upstairs:
Downstairs toilet: