I just had 2" x 8" limestone brick backsplash installed in my kitchen. I bought non-enhancing sealer, which the installer used on the tile before he grouted. It is now time to seal again and i am thinking I would rather use the enhancing sealer because the tile looks so cloudy and faded. Is it going to work to put the enhancing sealer on now over the non-enhancing sealer? Also, the grout looks much darker than the sample showed (Antique White) and there is very little distinction between the bricks (I wanted to see the tiles and not just a one color wall). Will the enhancing sealer make the grout darker? Should I use some sort of whitening pen on the grout after I seal the tile to make the grout stand out more?