Our concrete patio is discolored and could use whitening or bleaching to make it like new again. The patio measures about 11 feet by 20 feet. What would you suggest we do to make it like "new" again?

The fastest and most efficient way to clean concrete surfaces is with a pressure washer. A general residential type with around 2500 PSI and 2.5 gallons per minute is recommended. Using a pressure washer is not only more powerful than your garden hose, but it also uses a lot less water.

There are several pressure washer additives, such as ZEP driveway and concrete cleaner or M-1 House Wash concentrate that can be used with a pressure washer to remove heavy stains, mold or mildew.

When using the pressure washer to clean concrete, use a wide spray pattern. Avoid holding the wand in one place too long, or too close to the surface as it may etch the concrete. Always wet the surface first, before applying a detergent or concentrated cleaner. Move the wand back and forth in an even pattern of long strokes.

You may need to make several passes at stubborn stains. I would also suggest that you work within easily identified sections, such as between the expansion joints in the concrete.

Your question mentioned "bleaching" the concrete. Depending upon the type of stain, this may not be necessary. However, there are products (such as M1 House Wash) that can be mixed with a solution of bleach and water to be used within a pressure washer.

The type of stain will determine the type of solvent to use when cleaning your concrete. Some of the more common types of stains are iron, oil, paint and mildew. Just remember to test the solvent first, apply only to wet surfaces, rinse thoroughly and always wear protective clothing.

Dave Foster is the store manager for the Home Depot in Brentwood.