Clean Freaks Co. Pool deck care in Los Altos Hills.

A Los Altos Hills pool surround rarely reads as one material. The coping is often honed limestone or travertine; the field may be flagstone, tumbled pavers, exposed aggregate, or a troweled cool-deck acrylic — each with a different hardness and a different tolerance for pressure. Push travertine or a cool-deck coating at the setting a concrete driveway shrugs off and you etch the stone or strip the topping, and a poolside surface shows that damage in raking light.

Then there is the site itself. The Mid-Peninsula marine layer parks over these hillsides through much of the year, and a deck set into an oak-shaded slope dries slowly. That standing fog moisture, plus tannin and leaf litter shed by the coast live oaks overhead, feeds a film of algae, black lichen, and biofilm that a garden hose only smears from one plank to the next. On the north or tree-shaded side it turns genuinely slick underfoot — a footing hazard at a poolside, not merely a cosmetic one. Left alone through the wet months, that film thickens into the dark lichen crust that stains coping and dulls the stone for the rest of the year.

Finally, the deck sits near the top of a graded lot. Wash water carries loosened organics, and if it sheets into the pool it clouds the water and loads the filter; if it runs unchecked downslope it becomes a neighbor’s problem. The work has to be contained, directed, and kept clear of the coping joints and the water itself.

1. Every surface is identified before any water runs — coping stone, field material, and any cool-deck coating are tested for hardness and finish, and pressure and nozzle are set per zone rather than run at one setting across the whole deck.
2. Biological growth is lifted with dwell-time chemistry, not brute pressure — a controlled soft-wash treatment kills the fog-fed algae, lichen, and biofilm at the root so it does not return within weeks, sparing soft stone and acrylic toppings.
3. Wash water is contained and directed away from the pool and off the downslope edge — organics and runoff are captured or channeled so nothing clouds the water, overloads the filter, or sheets onto the property below.
4. Coping joints and material transitions are finished by hand, oak debris is cleared from expansion gaps and deck drains, and porous stone is re-sealed where the surface and season call for it. A light final rinse is drawn away from the water so the pool chemistry is left untouched.

• Late spring, before the swim season opens — after a wet winter of fog and rain has left the shaded side slick and before the deck goes back into daily barefoot use.
• Once the winter storm season closes, roughly March into April — when the marine layer and rain have driven the heaviest algae and lichen growth on the north-facing runs.
• Late autumn, as the coast live oaks drop — leaves and catkins fall into and after the first rains; clearing them keeps tannin from staining stone and coping over winter.
• Whenever the tree-shaded side greens over or feels slick underfoot — fog-fed biofilm is a footing hazard at a poolside long before it looks bad from the house.
• Ahead of a summer gathering — when the deck will be walked barefoot and seen up close.