We have perfectly fine old toilet, which works fine and has no mechanical problems. I care for my mom, who suffers from dementia, and when she uses the toilet during the night, more often than not, she forgets to flush. This leaves her urine to sit and deposit/stain until I wake next morning to make sure the commode is flushed. Over time, this has caused heavy brown deposits (lime?) in the bottom of our porcelain crapper. I've tried to keep up, but they jes keep adding up and now even scrubbing with the new fangled hi-tech brushes with disposable pads can't remove the most heavy stains. I tried some Lime-Away, which cleaned up the lighter deposits, but the heavy darker one's in the very bottom remain. Any suggestions on what might remove these stains? Would muriatic acid be too much? Obviously, I don't wanna destroy the smooth porcelain glaze.
nb