Green Sukabumi Stone Pool: Care & Repair Guide

Sukabumi green stone is one of the most popular choices for pool surrounds in Sanur villas because its dark, speckled surface hides algae and pairs well with blue water. But it is porous natural basalt, so it drinks up chlorine, salt, and rainwater faster than you would expect. This guide walks through cleaning, stain removal, and knowing when a slab simply needs replacing rather than patching.

Why Sukabumi Stone Behaves Differently

Sukabumi stone comes from volcanic deposits in West Java. It is hard enough for outdoor use but still has microscopic pores that absorb liquids. In Sanur, three things accelerate wear: constant sea-spray carrying fine salt crystals, PDAM or well-water minerals (especially iron) that leave orange traces, and the long rainy season from November to April when standing moisture keeps the surface damp for weeks.

Older villas built before 2010 often used thinner slabs with less consistent density. If your pool surround was installed without a proper sealant layer, the stone will look chalky within two or three years. That is normal porosity showing through, not structural failure.

• Porous basalt absorbs pool chemicals and rainwater quickly
• Sea air in Sanur adds salt that etches unsealed surfaces over time
• Well water with high iron content leaves rust-coloured streaks on coping
• Rainy-season humidity keeps algae spores alive on shaded sides of the pool edge

Cleaning Without Damaging the Surface

Start gentle. A soft-bristle broom and plain water remove most dust, pollen, and light algae film. For weekly upkeep, sweep dry leaves off the coping before they decompose into tannin stains.

For monthly deep cleaning, mix a mild pH-neutral detergent (the kind you would use on natural stone floors) with warm water. Apply with a sponge, let it sit no longer than five minutes, then rinse thoroughly. Avoid any product containing hydrochloric acid, phosphoric acid, or undiluted chlorine bleach directly on the stone – these break down the surface matrix and make future staining worse.

A pressure washer can help on heavily soiled areas, but keep the nozzle at least 30 cm away and use a wide fan tip. Too close, and you will blast out the fine mineral grains that give Sukabumi its speckled look.

• Weekly: dry brush or leaf blower to clear debris
• Monthly: pH-neutral cleaner, sponge, short dwell time, full rinse
• Never pour undiluted chlorine or acid cleaners onto bare stone
• Pressure-wash only at low setting, wide fan, 30+ cm distance

Stains, Etching, and Discolouration

The most common stain in Sanur pools is iron spotting from well water – orange-brown rings where water dripped off the coping during backwashing. A chelating agent designed for natural stone, applied with a soft cloth and left for ten minutes, usually lifts it. Rinse immediately after.

Chlorine etching looks different: a dull, matte patch where the glossy surface has been eaten away. This cannot be cleaned; the material is gone. Light etching can sometimes be smoothed with 400-grit wet-and-dry sandpaper followed by re-sealing. Deep pitting means that section should be replaced.

If you are mixing pool chemicals to treat a green-water episode, do not combine chlorine-based products with any acid or ammonia product. The fumes are dangerous. Step back, ventilate, and call your pool technician before adding anything else.

• Iron/rust spots → chelating cleaner for stone, short contact time, rinse fast
• Chlorine etch (matte patches) → light sanding plus reseal, or replace if deep
• Organic stains (coffee, wine, algae) → baking-soda paste, gentle scrub, rinse
• White calcium deposits from PDAM water → dilute vinegar on a cloth, never poured directly

Replacing a Slab or Coping Piece

A single cracked or spalled piece does not mean a full resurface. A mason can cut out the damaged slab, prepare the bed, and set a new one. Because Sukabumi is quarried in batches, colour variation between old and new pieces is normal – aim for a slab from the same quarry lot if possible, or accept a slight tone shift that will look natural over time.

The critical step most DIY attempts skip is the adhesive and sealant layer. Use a polymer-modified thin-set mortar rated for wet areas, and apply a penetrating sealer to the new slab before it cures fully. In Sanur's humidity, skipping this means the replacement starts absorbing pool splashes within a season.

• One bad slab does not equal a full job; local masons handle spot replacements well
• Match quarry batch where possible; slight variation looks natural
• Always use wet-area-rated thin-set mortar, not ordinary cement
• Seal the new piece before first exposure to pool water

Ongoing Care Routine

Twice a year – just before the rainy season (October) and after it ends (May) – walk the entire pool perimeter with your hand flat on each slab. Any piece that feels loose, spongy, or has a visible gap at the joint needs attention before monsoon rain works it further out of alignment.

Reapply a penetrating stone sealer every eighteen to twenty-four months. You will know it is time when water no longer beads up but soaks in immediately. Quick test: drip a few drops of clean water on an inconspicuous corner. If it darkens the surface within thirty seconds, it is time to reseal.

• Pre-rainy-season check (Oct/Nov): inspect joints, clear algae under coping
• Post-rainy-season check (Apr/May): remove debris from expansion gaps
• Re-seal every 18–24 months; the water-bead test tells you when
• Keep pool pH stable; wild swings accelerate stone degradation
• Store chlorine and acid products away from the pool deck area

Questions