Acids  are often used to clean grout because it’s believed to be a seriously difficult surface to clean.  The problem with this is that grout is not to be cleaned with acids according to the labels from the grout manufactures.  Acids cause a variety of problems including:

MaxOut Deep Grout Cleaner is a specifically designed formulation that emulsifies grease and dirt from your grout. It will not harm ceramic, porcelain, Saltillo, Terracotta or stone tile. This well established technology, using emulsifiers, works quickly on grease and dirt allowing for faster cleaning of grout, resulting in less time on the job. When used correctly, MaxOut Concentrate removes stubborn surface grime with simple agitation.