There must be dozens of ways to clean a concrete patio, but I am going to give three ways that I have found to be best. Not all concrete patios are created equal. Some may be more difficult to clean due to age and condition.
Pressure washing to clean a concrete patio
If you decide to do things an easier way, you may choose a pressure washer to clean your concrete patio. It seems it is not the pressure only that cleans the concrete, but also the product you use when pressure washing. If the concrete is stained with grease, you will need to use a degreaser. Apply this to the patio and allow it to sit for the recommended time listed on the package. Once you feel the degreaser has had time to work, use the pressure washer. You should be satisfied with the results if you are using a quality product. If you are not sure which product is best, consult with someone in a home improvement store, or check online for product reviews.
When you are trying to remove rust stains from a concrete patio, you must use a product that is designed to remove rust. Keep in mind different cleaning products promise different results.
Using elbow grease to clean a concrete patio
This is probably the way the previous generation would have cleaned a concrete patio. Use a scrub brush, your favorite laundry soap mixed in a bucket of water, and apply the mixture to all of the concrete that needs to be cleaned. Once you have covered the patio, allow the solution to sit for a few minutes so that grime and dirt is easier to remove. Rinse a small area, and scrub with the scrub brush. Yes, this is hard work, but you will be happy with the results.
Using a garden hose and bleach to clean a concrete patio
This is probably the least expensive, and least labor intensive ways to clean a concrete patio. Wet the entire area of concrete you want to clean. Pour bleach straight from the container onto the patio. Allow the bleach to sit for a few minutes, and you will notice the concrete beginning to look cleaner. After about fifteen minutes, rinse a small area of the concrete and determine if the bleach has worked itís magic yet. Rinse thoroughly when complete. You should find your concrete patio is now several shades cleaner.
Depending on how much effort you want to put into it, one of these manners of cleaning a concrete patio should work for you. Once you have tried this you will see why those who do it for a living charge what they do!