Deep cleaning grout is a tough job, even for Pros. Zep Grout Cleaner and Brightener contains strong but safe acids that act as a stain remover for grout lines. This professional strength formula quickly restores stained grout lines on tile floors without the need for heavy scrubbing. The formula is not abrasive to tile surfaces. Great for white and colored grout Deep cleans grout lines and lifts stains with little or no scrubbing. Trusted to remove tough old stains from grout and keep color intact Bleach-free professional strength formula Quickly cleans and brighten grout lines on floors Works well on shower floor grout, bathroom grout, and ceramic tile grout Removes light rust stains off concrete