cleaning Tile

I am trying to clean the grout in two bathrooms . The grout is white but has turned to a tan color. I have tried TSP, over the counter tile cleaners, Bleach none of these have done the trick.I was thinking about Meriodic acid sprayed lightly . Taking the grout out and re-grouting would not be cost effective. Any suggestion?
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On Sat, 25 Oct 2003 13:39:35 GMT, "Sacrameto Dave"

Removing the grout is the way to go. When it is regrouted, make sure to seal it. I do not recommend muratic acid--it weakens the grout and hazardous stuff to use and store.
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The best way to clean grout is with a quality dry vapor steam cleaner. The steam will penetrate the porous surface and float the soap bacteria and scum out so you can wipe it up. If you have the common two inch tiles with eighth-inch grout lines, you could use a brass brush to lightly abrade the surface if the nylon brush doesn't give desired result. As a last suggestion, use one part phosphoric acid to four parts water. This is an etching compound and will erode the grout surface after short exposure. Once the acid starts bubbling the grout line, rinse thoroughly down the drain. It is important to remove all residue because the chemical will even etch the ceramic on tile. Unfortunately, nothing but grout replacement may work at this point. The bleach has likely changed your grout color.
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