Cleaning and Maintaining Grout
Sealing is the most important thing you can do to protect your grout. Properly applied, sealer will protect the color and help prevent stains and water penetration. Keep in mind that it may need to be re-applied every few years or so, depending upon the durability of the sealant you choose. Follow the directions provided by the manufacturer.
To clean grout, use a non-acidic product. Do not use oil or wax-based cleaner, as these can leave residue.