Quick answer: Concrete cleaning needs enough pressure to lift soil and enough GPM to carry it away. Start with the least aggressive setup that works on a test patch. Old, damaged, or decorative concrete can be etched by excessive pressure.
Match the surface
A sound driveway may tolerate more pressure than a weathered patio, mortar joint, coating, or decorative finish. Check for cracks, loose aggregate, and sealers before cleaning. Test a hidden area with a wide nozzle and increase cleaning power gradually. Never aim the jet at people, pets, or fragile adjacent materials.
Why flow matters
Higher GPM moves more dirty water and can help a surface cleaner work efficiently. PSI describes pressure; GPM describes volume. A machine with high PSI but very low flow may clean a narrow strip slowly. Compare both figures at their rated operating point, not unrelated maximum claims.
Get an even finish
Sweep debris first and use a compatible cleaner when needed. A correctly sized surface-cleaner attachment can reduce striping on broad areas; verify its pressure, flow, and fitting limits. Keep passes consistent, rinse residue away from drains and planting, and follow local runoff rules.
Need help matching these checks to a specific model? Ask the KayrosTool team with the product name and your intended use.