MORE ON CLEANING GROUT:

If you take a toothbrush and scrub it a bit, *some* stans will come out.

And if you move heavy stuff around a lot, it also isn't a good choice, moving really heavy things is about the only thing that will break tile floor. We have two broken tiles; one from droping the piano, one from droping a heavy-duty tool. (I can't think of the name, that thing where you turn the rod and it gets tighter... lol, we use it to crack coconuts )

BTW: we've also dropped the coconut itself, which didn't break the tile.