Again, have never had to use bleach or peroxide (oxygen bleach) to clean tiles, and do not recommend it. I have been cleaning tile and stone, restoring Saltillo and stone for ten years. If it is oil based, a degreaser will cut it. If it is calcium/lime buildbup, acid will do it because it will not damage porcelain in 95% of the cases. I'm guessing it is grout haze based on the fact that it is reletively new. A good grout haze remover will take care of this problem, coupled with a bit of elbow grease and an alkaline cleaner to neutralize the acid, followed by a good rinse and seal. Bleach will do NOTHING in either case, oil or calcium. It will only create more problems with fading of pigment in the grout and furthering problems with haze, whether it be oxidation or a reaction causing efflourescence. If it is epoxy grout, you may need methylene chloride (paint stripper) to get it off. Very nasty stuff, but will work. Wear gloves, goggles, etc.
I realize this problem has probably been taken care of by now, but this is good info for all to read.
Last edited by azclean; 07-22-2009 at 10:54 PM.