My shower has hard water buildup and now looks cloudy. It is marble.

http://www.countertopspecialty.com/cleaning-hard-water-stains-on-marble-and-granite.html

I treat my tile with baby oil to regain its shine and it also adds a great water repellent. Just make sure you rub it in real good on the floor so not so slippery.

Hard water stains are from calcium buildup. You can use anything from vinegar (a mild acid) to a commercial product like CLR. If you don't want to go with anything harsh, you can make a paste using baking soda and water, too. Once the buildup is gone, there are a number of things you can do to keep the hard water from building up again. Just like before, you can simply use a thin coat of mineral oil or baby oil OR you can get a commercial marble/granite shine product. Since you can't take the calcium out of your water, try using a squeege and or chamois to dry off the walls of the shower when you're done. It takes a minute, but your hard water stains will reduce to a minimum. Cheers!

do not use VINEGAR or CLR it pits the marble.use dry #ooo steel wool and buff off calcium build up .then vac.up steel wool crumbs so it does not leave rust on marble. Apply a marble protection on before use .marble is nice to look at but a lot of work if you use it every day.

There is a product called BAR KEEPER that I found out about when I was researching the internet for calcium buildup on my glass shower door. This stuff is AMAZING! It is in a can like Comet and is in the same area in the store where you would find Comet.

I love Magic Erasers to remove soap scum from my tile walls. Wonder if they would work on your marble. I agree with others that, after it has been cleaned, the marble needs to be sealed with oil or some commercial marble sealer.

I've cleaned up my shower tile with tooth paste. It took some work because the previous owners never cleaned the calcium off but it did a good job and it smells great! Go to the dollar store and get whatever they have for a $1.00. Also, try it in a small area first to see if it is abrasive to the marble.

Been there, done that. WD-40. It will take some elbow grease, but will not scratch, discolor or mar the marble in any way. Works on glass and metal too. ( Found out the hard way with metals as other "guaranteed" products took the finish completely off.) Did my parents shower stall (30 years old) and looks brand new.

I like to use a cleaner made from vinegar, Baking soda, And Dawn.

straight vinegar

For a more durable and easy care method, after getting it clean again (000 steel wool, barkeepers friend, old dutch cleanse, NO acid!), use a marble sealant from the hardware store rather than an oil or wax, they can alter the color of the marble. Marble is very soft and porous, and once oil gets on it it can't really be removed.

Yes that's the correct name and I have heard that it comes in the creamy version.

I have used a razor blade to remove my hard water residue in my shower...works ell but takes time or you could try using Tidy Bowl....

use ONLY marble cleaners!!!

http://www.themarblecleaner.com/remove-water-stains-marble/

Bar keepers friend is also in a liquid form.

I used a pressure washer to clean mine, worked like a charm an no chemicals!