Concrete surfaces like driveways, patios and paths are constantly exposed to the elements. Over time, green algae, black spots and deep-set grime begin to build up.
Many homeowners reach straight for a pressure washer.
But pressure washing isn’t always the best solution.
In fact, it can:
-
Damage the surface
-
Remove jointing sand
-
Leave uneven “tiger stripe” marks
-
Force water into cracks
So what’s the better way?
Why Concrete Turns Green & Black
Concrete is porous. That means it absorbs moisture.
When moisture sits in the surface, it creates the perfect environment for:
-
Algae
-
Moss
-
Lichen (black spots)
-
Organic staining
The key is treating the root of the growth — not just blasting the surface.
The Safe Method: Chemical Treatment First
Instead of pressure washing first, professionals treat concrete with a high-strength exterior cleaner designed to:
-
Kill algae at the root
-
Break down black lichen staining
-
Lift deep-set dirt from pores
Once treated correctly, the surface often:
-
Brightens significantly
-
Requires little to no pressure washing
-
Stays cleaner for longer
Step-by-Step Guide
1️⃣ Remove loose debris with a stiff brush.
2️⃣ Apply a professional concrete cleaner evenly across the surface.
3️⃣ Allow it to dwell and penetrate the pores.
4️⃣ Lightly rinse if required.
No aggressive blasting needed.
Why This Method Lasts Longer
Pressure washing alone only removes surface dirt.
Chemical treatment:
-
Kills spores
-
Slows regrowth
-
Cleans deeper into the concrete
That’s why professionals always treat first.
What About Black Spots?
Black lichen is the hardest staining to remove.
It anchors itself deep into the surface.
The key is:
-
Using a strong enough formula
-
Allowing proper dwell time
-
Avoiding weak, diluted supermarket products
Final Thoughts
If your driveway or patio is:
-
Slippery
-
Green
-
Covered in black spots
-
Looking tired and weathered
You don’t necessarily need a pressure washer.
You need the right treatment.
Using a professional-strength concrete cleaner first can transform the surface safely and effectively.
Shark Concrete Cleaner