Aleš Lombergar

Easiest way I’ve found to clean that is to make a solution of one quart of warm water and a tablespoon of vinegar. The mild acidity of the vinegar will disolve the minerals in the stains and make your glass squeeky clean. If you want to go the commercial chemical route, there are a number of good tub and tile cleaners available at your local grocery. You can also check at your local hardware store.
Here are a few sites with good information on such products:
http://pubs.acs.org/cen/whatstuff/stuff/…
http://artistcraft.com/Cleaning/Cleaners

And then, there’s home recipes for tub and shower cleaners:

Borax works great to get at those hard water stains, and all the other nastiness that collects over time in your tub in shower. Use it as you would a powder cleanser, and rinse well after scrubbing.

“I’ve found the best thing to clean our tub is to wipe it down with white vinegar then pour baking soda all over it, let it sit for awhile, then scrub as you would with scouring powder. Also works great on the faucets – sprinkle baking soda on stainless steel faucets, wrap with rag, pour vinegar over rag and let soak for awhile. This gets the stainless steel sparkling.” Submitted by a reader at http://www.kitchencraftsnmore.net/recipe…

“You can use a rinse agent for the dishwasher in a spray bottle with water to keep soap build-up and water marks off your tub and shower.” (Submitted by Susan)

there is a product called CLR it will take care of the problem with no scrubbing. just spray it on and wipe it off with a sponge. Do let it set for about 5 mins super easy

lime away find it at any hard ware store or lowes , home depot etc.

Tilex with soap scum remover! Windex may sell something that prevents hard water stains, but I’m not really sure. So I can’t answer the portion of your question dealing with prevention. But definitely get that Tilex, it works wonders!

First of all, the doors HAVE to be squeegeed after each shower. Make it a habit. Otherwise your cleaning job is so much more difficult. I use BAM or CLR once a week followed by Windex.

Try CLR let it soak first.Also try vinegar and baking soda mixture.

Use the hand cleaner that mechanics use – Goop or GoJo work really well.It’s also good for polishing silver and removing stains on carpets! 1000’s of uses. As for prevention, treat your shower doors with RainEx.The product for Automobile windshields.

Mix a product called Lemi-Shine (about 1/2 cup) and 1 cup vinegar and 1-2 cups water in a spray bottle. This stuff works miracles. I buy Lemi-shine at Walmart for about $3 and it lasts about 6 months. It is actually a product made for your dishwasher to make glasses sparkle.