If your concrete stains are green in color, it indicates the presence of mold or algae—which you should address right away. If left unattended, mold will spread to other areas throughout the home. However, be careful not to disturb mold on indoor concrete surfaces and work with a local mold remediation specialist for specialized care. Once free from mold and algae, seal your concrete to eliminate pores and gaps.

If your garage floor is heavily soiled or stained, then it’s a good idea to powerwash it with a concrete cleaner before sealing. This process will remove dirt and debris to help the new sealer bond to the concrete properly, and it will also improve the look of your sealed garage floor. After power washing your floor, make sure you let the concrete dry completely before applying sealant, usually for 24 to 48 hours.

The ideal PSI (pounds per square inch) for a pressure washer depends on the surface you are cleaning. For general home use, a pressure washer with a range of 2,000 to 3,000 PSI is recommended and powerful enough for most residential projects.

The specific PSI you should use varies by task:

• High-Pressure Tasks (2,500-3,000 PSI): Tough materials like concrete, stone, masonry, and brick can handle higher pressures. This is suitable for removing stubborn stains from driveways or cleaning graffiti.

• Low-Pressure Tasks (around 600-1,300 PSI): Softer surfaces require a gentler touch to avoid damage. Use a low PSI setting for cleaning wood decks (especially softwoods like pine and cedar), vinyl siding, outdoor furniture, and stucco.

For best results, choose the right nozzle for your surface, such as a 15-degree nozzle for siding or a surface cleaner attachment for driveways. Using an extendable wand can also make the work easier and more ergonomic.

Whether you need to winterize your pressure washer depends on where it will be stored. If it's kept in a location where temperatures could drop to freezing, any liquid left in the water pump can freeze, expand, and cause severe damage to the machine. To prevent this, you can add antifreeze to the pump. While emptying the machine with compressed air is an alternative, it can be a tedious process and may not remove all the liquid. If you can store the pressure washer in a relatively warm place with no risk of freezing, you won't need to add antifreeze. However, regardless of storage conditions, it is good practice to empty the gas chamber and refresh the oil before storing it for the winter.