Christine,
I know how awful the hard water stains are in tub and toilets. We move to Northern Nevada from Boston and it has been awful. The water leaves awful stains everywhere. I clean house for a living, and have found a magic cleaner for all the hard water stains, the calcium deposits, etc., from the water.
Go to a restaurant supply house or Farmer Bros. Coffee if you have one close by and ask to purchase a package of grill screens. They are brown rectangular screens about the size of your hand, used to clean fry grill surfaces. They have one side that's a big rougher than the other. Use the roughest side and scrub the ring out of your toilet and the hard water marks out of the tub. It will take hard water deposits off the fixtures as well.
They work like a miracle. They won't scratch the surface of your tub or toilet and they won't scratch your fixtures either. I get them wet and scrub away. No cleaner, just water and some elbow grease. Although if you catch the stains before they've built up for a long time, they come right off with little or no effort.
I asked our Farmer Bros. rep here in Elko who first discovered the screens would clean the hard water deposits and he said the women have been buying the screens from him for years. Don't know who figured it out, but it's the best thing I've ever used. It sounds fishy and too good to be true, but I promise you'll never go back to anything else once you get your hands on these little screens. They work faster and better than a pumice stone.
For buildup in the dishwasher, you'll have to use some kind of commercially made cleaner. I believe Cascade brand makes a dishwasher cleaner, I think someone might have mentioned it in another post. It sits upside down in the silverware basket in an empty dishwasher and works like a charm.
Let me know if you have any questions about the grill screens, you won't be disappointed!
G.