Cleaning grout in a pebble tile shower
We have a shower that is natural pebble stone top to bottom. What will clean the grout easily without hurting the stone? I've tried scrubbing it with an ammonia solution, but it takes forever and the places we stand never get really clean. We have a little iron in our water that stains it and it's just a little dirty looking no matter what. I want to get it really clean before re-sealing it but only harsh chemicals do the trick and those can etch the stone. Help!