Green water in your Sanur villa pool is almost always an algae bloom, not a mystery chemical problem. The warm air, high humidity, and occasional heavy rain showers create perfect conditions for algae to multiply faster than your chlorine can keep up. With a proper shock treatment, thorough brushing, and a few days of continuous filtration, you can usually get back to crystal-clear water within a week.
Why Your Pool Turns Green
In Sanur, pools sit outdoors under direct sun most of the year. Algae spores are everywhere—in the sea breeze off the beach, in rainwater that washes leaves into the basin, even on the shoes of staff walking around the garden. One missed day of circulation or a dip below 1 ppm free chlorine and the spores start multiplying visibly within 24 to 48 hours.
The rainy season (roughly November through March) makes things worse. Heavy downpours dilute your chlorine overnight, drop the pH, and stir up organic matter from surrounding vegetation. If your villa draws from a well-fed rooftop tank or PDAM supply with slightly higher mineral content, the chemistry shifts a little more each time you top up.
- Free chlorine drops below 1 ppm after rain or heavy bather load
- pH drifts above 7.6, making chlorine less effective
- Organic debris—leaves, pollen, bird droppings—feeds algae
- Filter not running long enough during hot spells
Shock Chlorination: The Core Step
Shock treatment is the single most important step. You need to raise free chlorine to roughly 10–20 ppm for several hours so it kills existing algae rather than just inhibiting it. Use a non-stabilised shock product if possible, because Sanur's strong UV already adds stabiliser through sunlight and excess CYA locks up your available chlorine.
Safety note: never mix different chlorine products in the same bucket, and never add acid or algaecide alongside shock. Mixing chemicals can release toxic gas. Add shock directly into the pool water at night when no one is swimming, then let the pump run continuously.
If you are unsure of the exact dose for your pool volume, send a photo of your test-strip reading and the pool dimensions on WhatsApp and I will calculate the right amount before you pour anything in.
If your pool still looks off after trying these steps, snap a photo of the water and your latest test-strip reading and send them over on WhatsApp—I will tell you exactly what to do next before you spend money on more chemicals.
Brush the Walls and Vacuum the Bottom
Algae clings to tile, plaster, and vinyl liner. Even after the water looks clearer, dead algae sits on every surface and re-releases nutrients if you skip this step. Use a stiff-bristle brush (nylon for plaster, softer for vinyl) and work from the deep end upward, spending extra time on the waterline where the film is thickest.
After brushing, vacuum the entire bottom to waste—do not recirculate. In older Sanur villas with rougher finishes you may need two passes. The first lifts the bulk; the second catches what settled back down while you were working.
- Brush all walls, steps, and the waterline band
- Vacuum to waste, not backwash
- Repeat brushing plus vacuuming on day 2 if the water still looks hazy
Run the Filter Correctly
Once the shock has done its job and the visible green fades (usually within 12–24 hours), switch the filter to continuous circulation. For a typical villa pool of 40–80 m³ that means running the pump 16–24 hours a day until the water runs completely clear through the return jets.
Backwash the sand or cartridge filter once turbidity drops below 5 NTU, then rinse for 30 seconds before returning to normal filtration. If your villa uses a cartridge system, pull the cartridges out, hose them off under a garden tap, and check for tears before reinstalling.
How Long Does It Take?
For a mild bloom—water is yellow-green but still somewhat transparent—you can expect clarity in 3–5 days with daily brushing, continuous filtration, and one follow-up half-dose of shock on day 2.
A heavy bloom where you cannot see the bottom will take closer to 7–10 days. You may need two full shock doses spaced 48 hours apart. During this period keep the cover on at night to reduce evaporation loss and limit new spore entry from rain.
If after ten days the water is still cloudy or turning green again, there is likely an underlying issue—a leaking skimmer pulling in organic matter, a clogged filter element, or a pH that keeps drifting. That is when it pays to have someone come look rather than keep dosing blindly.
Keeping It Clear Through the Rainy Season
Prevention is far cheaper than repeated shocks. Aim for free chlorine between 1 and 3 ppm every single day, even if no one swims. In Sanur's humidity a small automatic chlorinator or a timed tablet feeder in the skimmer basket takes the guesswork out of morning dosing.
Check your pH twice a week (target 7.2–7.6). Keep CYA below 50 ppm so your chlorine stays active. Run the pump at least 8 hours daily during the dry season and 12+ hours through the rainy months. Skim the surface every morning—Sanur's coastal breeze drops fine sand and organic dust onto the water within hours.
- Test strips every morning; adjust before adding more chlorine
- Clean the skimmer basket and strainer pot weekly
- Cover the pool overnight during heavy rain
- Shock lightly (half dose) once a month as maintenance
- Inspect return jets monthly for biofilm buildup
Questions
Can I just add more regular chlorine instead of shock?
Regular chlorine keeps levels in the 1–3 ppm range, which inhibits algae but does not kill an established bloom. You need the concentrated hit from a shock product to push levels high enough to destroy cell walls. Think of it this way: maintenance chlorine is like brushing your teeth; shock is the deep clean when you already have plaque.
My pool turned green after one night of heavy rain. Is that normal?
Yes, especially in Sanur where downpours can dump 50 mm or more in an hour. The fresh water dilutes your chlorine below effective levels, lowers pH, and washes organic matter into the basin. It is not a sign of a broken system—just a chemistry reset. Follow the steps above and you should be back on track within a few days.
Should I drain and refill the pool if it is very green?
Only as a last resort. A full drain-and-refill costs time, water (PDAM supply can be intermittent), and resets every chemical balance from scratch. In most cases a proper two-stage shock with thorough brushing clears the water without losing volume. If the liner or tile is badly stained after the algae dies off, a professional acid wash may help, but that is a separate job.
I'll reply with what's needed, a price and when I can come.
