Killing the black ring..!

We are a four bathroom house with only two people living here. Two of the bathrooms are seldom used. About the only time we go into those rooms is for cleaning purposes.
The toilets develop a black ring around the water spot, which is difficult to get off, and looks really bad. Any suggestions on how to prevent the black ring..?
Thank you in advance.......

Black Ring

Are you using one of those handy cleaners that you put in the tank? if so and you have a black flapper on the flush valve it could be desolving due to the cleaner; a lot of parts in the toilet tank may have a prob. with certain cleaners.

vinegar and baking soda

Try pouring some cheap white vinegar and baking soda in the bowl. It's not as hard on rubber or plastic and it will keep a ring from forming for a week or so.

Anything gets dirty even when it isn't used, and that goes beyond toilets. My toilets at home are idle for most of the summer. Rings will form in them and the water gets cloudy. The rings come off easily with bleach and a brush. (This is water from a county wide municipal system and chloramine is used as a disinfectant).

I have never had rings in either of the toilets here in the cabin, and they use brook water that is sent through a sediment filter. My neighbors have shallow wells and their toilets are stained orange.

If the ring is hard to remove, use something like Lysol Heavy Duty Bowl Cleaner (which contains HCl) and then once it's clean, add a little bleach to the bowl water and leave it (and I am referring to the toilets that are not used often).

Good luck!

achutch