Florida pool decks grow things. Give a shaded paver or concrete deck a few months of humidity, sprinkler overspray, and summer rain, and a green-black film of algae and mildew appears — slick as ice when wet, and right where barefoot kids run. Here's how to clean it off and keep it off.

The oxygen-bleach scrub

  1. Mix: oxygen bleach powder (sodium percarbonate) in warm water per the package — roughly one cup per gallon for visible growth.
  2. Wet the deck first with the hose, then apply the solution with a stiff push broom or pump sprayer.
  3. Let it dwell 15 minutes, keeping it damp — reapply if it starts drying in the sun. The dwell does most of the work.
  4. Scrub with the push broom and rinse thoroughly toward a drain, not the pool.

Oxygen bleach is the pro pick here because it's tough on algae but far gentler on the surrounding landscaping and pool chemistry than chlorine bleach runoff.

Pressure washing: yes on concrete, careful everywhere else

Bare concrete handles a pressure washer fine — use a wide fan tip or surface-cleaner attachment and keep moving. Pavers need more care: high pressure blasts the joint sand out, which destabilizes the surface and invites weeds and ants. If you pressure-wash pavers, plan to re-sand the joints after, and consider sealing — sealed pavers shrug off algae for years.

Keeping it from coming back

  • Fix the moisture pattern: redirect sprinkler heads that spray the deck, trim vegetation that keeps zones in permanent shade, and clear drainage so rain doesn't pond.
  • Quarterly preventive rinse: a light application of the same oxygen-bleach solution before anything visible appears stops the colony from establishing.
  • Furniture rust rings: metal chair feet leave orange rings on wet decks — pop rubber caps on the feet and the rings stop.
Watch the runoff: never let chlorine bleach or strong cleaning solutions wash into the pool (it wrecks your water chemistry) or the storm drain. Rinse toward landscape beds only with plant-safe oxygen bleach, and pre-wet any grass it might touch.
Pro tip: test your deck's slipperiness the safe way — push a dry towel across it with your foot. If the towel glides where it should drag, the invisible film is already established and it's time for the scrub, even if you can't see green yet.