How do I get rid of a blue ring in my commode?

Bleach should take it out.

If a blue ring shows up in your toilet bowl, it will rim the bowl at the same height as the usual water level in the bowl.

The cause of the blue ring is elevated levels of copper in your water supply, which causes your water to be more acidic than is usual.

To get rid of blue stains in your toilet bowl, use a mixture of 1 cup water and 1 cup ammonia.

Pour it into the toilet and let it stand for ten minutes. Use the toilet brush to scrub away the softened stain, then flush the toilet.

Copper. You need to get a Metal Magnetizer for insertion in your tank. Metals gather to the Magnet and then once monthly you take off the tank lid To remove the Metals to a waste can. They sell these mostly anywhere. They last forever. They cost less than Extra Bleach. I got mine at www.fingerhut.com for $10. You can probably find one at Amazon.com.

Here is the link:

https://www.amazon.com/gp/aw/d/B0052LF2AU/ref=cm_cr_arp_mb_bdcrb_top?ie=UTF8