You should check out the tank. The tank is just a holding area and it does get grimy. It probably needs some serious scrubbing.

Also, put the seat down so the dog can't drink out of the toilet.

Sometimes the rubber washers in the mechanism in the tank get old and soft depositing black into the tank.

If this is the case, replacing the rubber washers should take care of the problem.

A black rubber 'flapper' in the tank will also cause discoloration. They get old and rotten - The newer red flappers are much better.

My plumber says those additives (Tidybowl, anything that hangs in the tank) are bad for the toilet plumbing works. So I only use a toilet cleaner like Lysol once a week. It keeps those greasy looking black rings away. Don't know exactly what causes the ring to form, whether it's bacteria, algae, or what?

I had been using bleach but then read that just'bleached' the ring but the ring still remained. My sister uses vinegar & that acid seems to actually remove the ring. She pours a consider amount in the bowl at night & lets it remain overnight in the bowl. I don't like the smell but hey, if it works! I think the type of water in the city system may have a lot to do with it also as my son's water on the other side of the same city also gets those black rings but the rings I have are not black at all. At times I also use one of those pumice sticks & it doesn't seem to scratch the bowl at all.

just been reading the tips and I use a magic eraser to clean my toilet, now scrubbing needed. Just cut a piece of one off and place in the toilet over night, take it out before you use it again, it really works, shines like new

flowerfarmer1: you're saying you just cut a piece of magic eraser off and leave it in your toilet overnight???

I don't see how that could possibly clean anything... magic eraser works because it is a mild abrasive... it works by rubbing, not just floating in water.

I'm confused. Please explain.