Cleaning a concrete patio means removing dirt, algae, and stains from the surface without damaging the concrete itself. The process usually involves sweeping away debris, applying a cleaner matched to the type of stain, scrubbing, and rinsing with a hose or pressure washer set to the correct PSI and nozzle angle. Stamped or sealed concrete needs gentler handling than plain broom-finished slabs.
If you’ve ever stood in your backyard wondering why your patio looks gray and blotchy no matter how many times you hose it down, the short answer is that you’re probably cleaning it the same way regardless of what’s actually causing the mess. Algae needs a different approach than an oil stain. A stamped patio needs a different approach than a plain slab. Get that match wrong and you either waste a Saturday or, worse, damage a surface that’s supposed to last decades.
We’ve resealed and resurfaced enough patios around Hoffman Estates to know exactly which cleaning habits shorten a patio’s life and which ones extend it. Here’s the breakdown.
For everyday grime, the basic method takes about an hour and doesn’t require anything you don’t already own.
This covers routine concrete patio cleaning. Stains, algae, and decorative finishes each need a slightly different move, which is where most DIY attempts go sideways.
Before any cleaner touches the surface, clear the deck, literally. Move furniture, planters, and grills out of the work zone so nothing blocks your scrubbing or gets damaged by splashback.
Test whatever cleaner you’re using on a small, hidden corner first. Stamped and colored concrete can react differently than plain gray slab, and you want to find that out on a two-inch patch, not the whole patio.
Pick an overcast day if you can. Direct sun makes cleaning solutions evaporate before they’ve had time to work, which means more scrubbing for the same result.
If your patio is older, uneven, or has cracks wider than a hairline, cleaning alone won’t fix the underlying problem. That’s usually the point where homeowners start asking about our patio installation and resurfacing work instead of another round of scrubbing.
Yes, but the nozzle and pressure setting matter more than most people expect. Too much pressure at too tight an angle can etch lines into the surface that never come out.
Here’s a rough guide by finish type:
| Patio Finish | Recommended Nozzle | PSI Range |
| Plain broom finish | 25 to 40 degree tip | 2,500 to 3,000 PSI |
| Stamped or decorative | 40 degree tip only | 2,000 to 2,500 PSI |
| Exposed aggregate | 25 to 40 degree tip | 2,500 to 3,000 PSI |
| Sealed concrete | 40 degree tip, wide distance | 1,500 to 2,000 PSI |
Concrete-product manufacturer Brickform recommends staying with a wider fan tip on decorative surfaces and keeping distance from the slab, since narrower tips built for stripping old sealer can gouge stamped or stained finishes. We’ve walked up to driveways where a rental pressure washer left a zebra-striped pattern that a homeowner then had to pay to resurface. It’s an easy mistake, and an expensive one to undo.
Keep the wand moving in even, overlapping passes rather than holding it in one spot. If you’re not confident about which nozzle you have on hand, use the widest one available and make more passes instead of turning up the pressure.
Green or black patches, usually in shaded or damp corners, are almost always algae or mildew rather than dirt. Regular dish soap won’t touch it.
Mix a solution of oxygen bleach and water, or a diluted household bleach solution if the concrete isn’t colored or stamped, and let it sit on the affected area for 10 to 15 minutes before scrubbing. Rinse thoroughly afterward so no residue sits on the surface or drains into the lawn.
Shaded patios under trees or near downspouts tend to grow algae back faster than sunny, well-drained ones. If it’s a repeat problem every season, the fix usually isn’t a stronger cleaner, it’s improving drainage or trimming back overhanging branches.
Concrete is porous, so oil and grease don’t just sit on top, they soak in. That’s why a quick wipe never fully removes them.
For fresh spills, absorbent material like kitty litter or sawdust pulls up what’s still on the surface. For stains that have already set, a poultice (an absorbent paste mixed with a degreaser) does the real work: apply it, let it dry completely, then sweep it away. A concrete-safe degreaser applied before scrubbing also helps loosen grease that’s worked its way into the pores.
A quick way to check how fresh a stain is: press a paper towel onto it. If the towel picks up residue, the stain is recent and will lift more easily than one that’s had months to set.
We don’t recommend it for a DIY cleaning job, and here’s the actual reasoning rather than just a warning label.
Muriatic acid is a diluted form of hydrochloric acid, and it doesn’t just clean concrete, it chemically reacts with it. Portland cement, the binder that holds concrete together, dissolves on contact with acid, which can leave behind a chalky white residue called efflorescence and weaken the surface over repeated use.
The handling risk is real too. According to CDC guidance on hydrogen chloride exposure, the OSHA permissible exposure limit is 5 parts per million, and NIOSH considers concentrations above 50 parts per million immediately dangerous to life or health. That’s a narrow margin for a backyard project without proper ventilation, gloves, and eye protection.
If a patio is stained badly enough that acid seems like the only option, that’s usually a sign the surface needs professional resurfacing or resealing rather than a harsher chemical.
Not sure if your patio needs a deep clean, a reseal, or something more? We can take a look and tell you honestly which one it is. See how this works for your situation.
Stamped and sealed surfaces need the gentlest approach on this list. Skip acid entirely, stick to pH-neutral or mild cleaners, and keep pressure washers on the lower end of the PSI range in the table above.
Before cleaning, check whether the sealer is still intact. If water beads up on the surface, the seal is doing its job. If water soaks in and darkens the concrete instead, resealing protects the color and pattern underneath and should probably happen before or shortly after your next cleaning.
Stamped patios in particular can lose color depth or texture definition if scrubbed with anything abrasive, including wire brushes or scouring pads. A soft-bristle brush and patience get the job done without wearing down the pattern you paid for.
A rough maintenance schedule looks like this:
○ Weekly: Sweep to keep dust and leaves from settling into the surface.
○ Monthly: Rinse with a hose to clear pollen, dust, and light grime before it sets.
○ Seasonally: A full clean using the steps above, especially after winter salt exposure or a summer of cookouts.
○ Every 2 to 3 years: Reseal to protect against staining and moisture damage.
That resealing window matters more here than in milder climates. Illinois winters put concrete through repeated freeze-thaw cycles, and de-icing salt tracked onto a patio from a driveway or walkway accelerates surface wear. We recommend resealing every two to three years for that reason, a little more often if the patio gets heavy foot traffic or direct salt exposure.
Homeowners here in Hoffman Estates dealing with a patio that’s been neglected for a few winters in a row usually find that one thorough cleaning and a fresh seal brings back most of the original look, without needing a full replacement.
○ Sweep, wet, apply a matched cleaner, scrub, and rinse for routine dirt and grime.
○ Match your pressure washer’s PSI and nozzle angle to your patio’s finish, wider tip and lower pressure for stamped or sealed surfaces.
○ Oxygen bleach or diluted bleach handles algae and moss. Let it sit before scrubbing, then rinse well.
○ Fresh oil and grease stains lift with absorbent material. Set-in stains need a poultice and degreaser.
○ Skip muriatic acid for DIY jobs. It can weaken the concrete and comes with real handling hazards.
○ Reseal every 2 to 3 years, especially in a climate with freeze-thaw cycles and road salt.
Ready for a second opinion on your patio? Whether it needs a deep clean, a reseal, or a closer look at cracks and unevenness, we’ll tell you straight what it actually needs. Find out if your patio needs more than a cleaning.
Is it safe to use bleach on a colored or stamped concrete patio?
Diluted bleach can be used on stamped or colored concrete in small, tested amounts, but oxygen bleach is the safer choice since it’s less likely to fade integral color or damage a sealer. Always test a hidden spot first.
What’s the difference between muriatic acid and oxygen bleach for concrete?
Muriatic acid is a diluted hydrochloric acid that chemically reacts with the cement in concrete and carries real handling hazards. Oxygen bleach is a milder oxidizing cleaner that lifts organic stains like algae and mildew without etching the surface.
How long should a patio dry before resealing?
Concrete should be completely dry before sealing, which typically means waiting 24 to 48 hours after a thorough cleaning, longer if the weather is humid or cool.
Can vinegar clean a concrete patio?
Vinegar is mildly acidic and can be used for very light cleaning, but it’s not strong enough for algae, oil, or set-in stains, and repeated use can dull a sealed finish over time.
Why does algae keep coming back on my patio?
Algae regrows fastest in shaded, damp areas with poor drainage. If it returns every season despite cleaning, the underlying issue is usually moisture and shade rather than the cleaning method itself.
