Pumie is so inexpensive and simple. It's a soft pumice stick that scrapes away the hard water ring in your toilet bowls. It can be used on several other surfaces, as well. According to the marketing copy on Amazon, Pumie also works on ceramic tile, porcelain, masonry, concrete and iron. However, I don't recommend using it on plumbing fixtures, such as drain stoppers, unless your sure it isn't covered in a painted metallic finish. I was getting hard water around my drain stoppers, and Pumie worked to remove the hard water there, too, but it also started to remove the chrome finish. I now know my drain stoppers are brass underneath that finish. (Fun fact: nothing is made with solid chrome. Instead, chrome plating is used. I learned this the hard way).
Pumie still takes a little time and elbow grease, but it's the only thing I've found that removes toilet bowl ring. There are several other similar pumice stones sold for cleaning toilet bowl rings that probably work just as well, but I haven't tried any other, so I can't testify to their effectiveness.
The pumice does wear away as you scrub. This part is actually useful, though, because the stick starts to form a slanted tip at the end, which helps you get the dark ring just under the rim of the toilet bowl, as well as other hard to reach places around your home that may have hard water deposits. Because it wears away, it needs to be replaced frequently, but it's cheap. I have a multi-pack shipped to me every couple of months using Amazon Subscribe and Save.
Have you found another great way to remove toilet bowl ring? Tell us about it in the comments below. I'd love to hear about it. I'm always searching for great cleaning hacks to share with my pre-listing consultation clients who are preparing a home for sale.