Cleaning grout in a limestone shower
All, I'm hoping someone here has a few product suggestions.
A few years ago we gut renovated our house and ended up with a lovely limestone bathroom. Because limestone can be a porous stone, and I've had some bad experience in the past, I've been hesitant to allow any kind of standard bathroom cleaners near the shower -- no scrubbing bubbles, no tilex, etc.
Well, 2 years later and I just noticed that some of the grout is turning a nasty black (I might've noticed earlier except I wear glasses and obviously don't wear them into the shower. Why my wife didn't saying anything I don't know.)
So... I'm looking for a way to clean the grout that won't harm the limestone. I could buy a few of the commercial products and test them in discreet areas but I'm hoping that someone here has gone through the process and can recommend one or another. Or an out-of-the-way product. Or even a basic "home remedy" like white vinegar.
So, any ideas?
Thanks so much!