Q. I have been using every Clorox product known to man to try to clean the grout in my shower. It has helped to some extent, but is not getting all the mildew (and I have even used straight Clorox and scrubbed it with a grout brush). After rinsing the tile with water (but probably not enough to remove all the bleach), will it be OK to use hydrogen peroxide on the grout? I know you can’t mix Clorox with ammonia or anything acidic but am not sure about hydrogen peroxide.

A. Sorry about the mildew problem, and I know how frustrating it can be trying to get it under control. I wonder if you have tried our Tilex line? (http://www.tilex.com) With your difficult problem, they may be worth considering.

It may be surprising, but using Clorox® Regular-Bleach full-strength is probably less effective than using these products. The Tilex products have special surfactants that help hold the bleach solution on the problem and aid in penetrating into the grout.

As for your last question, yes, it is OK to rinse with hydrogen peroxide after use. (Though, I would consider diluting it slightly.) The reaction between hydrogen peroxide and sodium hypochlorite, the bleach’s active ingredient, will produce oxygen unlike other products (ammonia and acids) which can produce toxic materials.