Hi,
How do I clean a white gritty substance on granite?
It's either limescale or calcium deposite. We have very hard water. Appreciate any ideas.

There are some stone refinishing experts at www.stoneadvice.com who can advise on what not to use as well as what to use to clean it. Or for a more personal touch try Tom McNall at tom@greatnorthernstone.com He owns a stone cleaning and restoration company and does know his stuff.