I bought a ceramic tile and grout cleaner but the product does not work very well on the grout. Yes, the tile is nice and clean but the grout is not as white as I want it to be. Does anybody know of a good grout cleaner (brand?) I used Mapai and (not sure if it is spelled correctly) it seemed like it worked very well but I ran out and went back to the dealer and they don't sell it anymore. Maybe I should go to Lowe's and check them out. Your thoughts. Thank you.