Not sure what the negative reviews are about
this stuff really does work.  If you have light hard water stains this stuff will remove it instantly.  If you have thick build-up you'll have to put some effort in, but you should be able to reduce it by at least 95% if not 100%.  Nine out of the ten areas I tried it on were restored 100%, and the tenth area still has some hard water residue left behind that I can't seem to remove.  I can live with that.  Not trying to be featured in architectural digest over here.<br /><br />When you consider that every other method I looked into either didn't work whatsoever, or couldn't be used on stone, I'm impressed.
Rating: 5 stars