Zep Commercial 172 oz. All-in-One Pressure Washer Concentrate Cleaner. It effectively removes dirt, oil, grease, and stains caused by algae, mold, and mildew. This versatile concentrate makes up to 26 gallons of cleaner and can be used in a pressure washer or manually applied to clean siding, driveways, brick, wood, stucco, and other surfaces.