a grout cleaner and brightener. People claim it takes years off old grout, lifts heavy stains, and works in minutes. I decided to try Zep on the grout of the porcelain floor tile in my bathroom.

Get the Black Diamond limestone and travertine floor cleaner at Amazon or BDStoneworks. We also tested the Zep Neutral pH floor cleaner. Zep is a brand we like, but unfortunately, this product ...