If your pavers have turned dark, green, or slippery, you're seeing one of Florida's most common hardscape problems. Heat, humidity, shade, and summer rain make Tampa Bay a perfect home for mold, mildew, and algae. They're unsightly, they can make a pool deck slick, and over time they hold moisture that shortens the life of your sealer.
Is It Mold, Mildew, or Algae?
| What You See | Most Likely | Where It Shows Up |
|---|---|---|
| Black or gray specks and patches | Mildew or mold | Shaded walks, covered lanais, north walls |
| Green film that feels slick | Algae | Low spots, pool edges, sprinkler zones |
| Dark streaks under roof edges and plants | Algae and mildew fed by runoff | Drip lines, downspouts, planters |
| Fuzzy green or gray clumps in joints | Moss | Damp joints with low sand |
| Orange or brown stains | Not mildew; see rust stains on pavers | Sprinkler and fertilizer areas |
Why Black and Green Stains Keep Coming Back
- Shade. Surfaces that never dry out in the sun grow mildew fastest.
- Irrigation overspray. Sprinklers that wet the pavers every morning feed algae all year.
- Poor drainage. Puddles and low spots stay wet for days after a storm.
- Organic debris. Leaves, mulch, and pollen give spores something to eat.
- Worn sealer. Once water soaks in instead of beading, the surface stays damp longer.
How to Clean Mildew and Algae Off Pavers
- Sweep and rinse to remove loose debris.
- Apply a cleaner made for mildew and algae on hardscapes. Wet nearby plants first and rinse them after, and follow the label for dilution and dwell time.
- Scrub with a soft brush or a surface cleaner on low pressure, never a narrow pressure washer tip held close.
- Rinse well so no cleaner is left in the joints.
On travertine, marble, and limestone, use only stone-safe cleaners. Acidic products etch calcium-based stone, and strong cleaners can strip or haze an existing sealer.
Why Sealing Helps
A sealed surface sheds water instead of soaking it up, so it dries faster after rain and sprinklers. That alone slows mildew and algae a lot. Sealing also fills the surface pores where spores take hold, which makes routine rinsing much more effective. Our paver cleaning treats the growth first, then sealing locks in the clean finish. For covered areas, see patio and lanai paver sealing.
Keeping Mildew Away Between Cleanings
- Aim sprinklers at the lawn, not the pavers, and run them early so surfaces dry by midday.
- Rinse pool decks and shaded walks every few weeks and treat small spots early.
- Trim plants that block sun and airflow along walkways.
- Keep gutters and downspouts flowing away from the pavers.
- Do the water test each spring; if water soaks in, the seal is worn. See how often to reseal pavers.
We clean and seal mildew-prone pavers and pool decks all over Tampa Bay, from shady lots in Carrollwood to waterfront lanais in Apollo Beach.
Shaded pool cages are the most common problem area. See caring for pavers under a screen enclosure.
I cannot say enough good things about this company. They truly are customer oriented. They scheduled an appointment for an estimate within a few days of us calling. They started on the paver sealing the following week, showed up early that morning and worked until 5pm. They took their time, paid attention to the little details and cleaned up around the doors. They wiped down the edge of the pool screen where some sealer had gotten on it. My pavers look brand new, and I could not be happier. Sam and Steve are both professional and courteous.
Mold, Mildew, and Algae on Pavers in Florida FAQs
What causes black spots on pavers in Florida?
Most black spots are mildew or mold growing in shade and moisture. Irrigation overspray, poor drainage, and leaves on the surface make it worse.
Can I use bleach on my pavers?
A diluted cleaner made for hardscape mildew works, but protect your plants, follow the label, and rinse well. Don't use strong or acidic cleaners on travertine, marble, or limestone.
Is algae on a pool deck dangerous?
It can make the deck slippery, especially near the water. Cleaning it off and sealing the deck helps, and slip resistant additive is available for pool decks.
How fast does mildew come back after cleaning?
On unsealed pavers in shade it can return within a few months. Sealing and reducing overspray usually keeps it away much longer.
Will pressure washing remove mildew?
It removes some of it, but it often leaves roots and stains behind and can blow out joint sand. A mildew treatment followed by a gentle rinse works better.
Does sealer stop mildew completely?
No sealer stops it completely in Florida, but sealed pavers dry faster and clean up much more easily, so growth is slower and lighter.