Real-life case: green water on Saturday morning (fixed by Sunday evening)
- The situation: green water discovered on Saturday morning, family barbecue planned for Sunday evening.
- The timeline: brushing + photo test at 8:30, pH corrected at 9, calculated shock at 11, continuous filtration, clear water by Sunday noon.
- The deciding factor: a shock calculated on the real volume and level — not the forum's "universal" dose.
- Swim verdict: best avoided Saturday, ideal again Sunday afternoon, confirmed by re-test.
Saturday, 8:05am. Coffee in hand, shutters open: the pool is green. Not full-on duck-pond green, but unmistakably green, with walls that feel slippery under the net pole. Sizeable problem: Sunday evening, fifteen people are coming for a barbecue, children and swimsuits included. Here’s the real hour-by-hour story of a guided rescue — exactly the kind of weekend the app was built for.
Saturday morning: diagnosis in 30 seconds, plan in 2 minutes
8:30. A vigorous brushing of the walls and floor — dislodged algae die faster — then a strip dipped and photographed. The app reads: free chlorine on the floor, pH too high, stabiliser fine. Diagnosis: classic algae after the week’s heat, sanitisation down, pH taking advantage of the situation. The health score hurts, but the plan appears: six steps, with timers.
9:00. Step 1 of the plan: correct the pH first. It’s the move most people skip — and the number one reason shock treatments fail: shock chlorine in high-pH water loses most of its strength. The pH-reducer dose calculated for the pool’s 42 m³, poured in, filtration running.
11:00. Quick re-test: pH back in range. Green light from the app for the shock step: the dose is calculated on the volume, the actual product (an off-the-shelf shock chlorine, scanned into the app) and the starting level — not “a kilo, because that’s what the forum says”. The swim indicator switches to “best avoided” with a countdown: nobody in the water today, as planned.
Saturday afternoon → Sunday: the filtration does the work
All afternoon. Continuous filtration — the timer ticking away on the phone’s lock screen, zero mental load. The water goes from green to grey-green: the algae are dying and turning pale, exactly the expected sequence (the moment when, without an explanation, many people panic and re-dose at random).
Sunday, 9am. Water nearly clear, a residual whitish haze — dead algae in suspension. Filter cleaned (the pressure had climbed), photo re-test: chlorine still high but falling, pH stable. The app keeps “swimming best avoided” and estimates the all-clear for the afternoon.
Sunday, 3pm. Re-test: chlorine back in range. The indicator switches to “swimming ideal” — confirmed by measurement, not by guesswork. The water is crystal clear, the walls no longer slippery.
Sunday, 7pm. Fifteen guests, sparkling water, and nobody suspects a thing. Total cost: one morning of attention, two properly dosed products, zero panic.
What this case teaches
Three lessons apply to every green pool. Speed pays: caught on Saturday morning, the whole business is wrapped up in 36 hours; the same water ignored for a week becomes a five-day project. pH first, always: it decides whether your shock works at full strength or at half. The calculated dose changes everything: the same protocol with an underestimated generic dose would have made the green “retreat”… only to return on Wednesday.
Frequently asked questions
Is 24 to 36 hours realistic for rescuing green water?
For light-to-medium green water caught early, yes: a well-dosed shock + continuous filtration do most of the work in 24-48 h. "Thick soup" neglected for weeks will need more like 3-5 days and flocculation.
Would the barbecue have been ruined without treating on Saturday?
Probably: green water never improves on its own in summer — it gets worse. Every day of waiting adds work. Speed of reaction is the real hero of this case.
And if the shock hadn't been enough?
Plan B is built in: re-test, check the stabiliser (the classic shock saboteur), and a second properly dosed round. The app chains these steps if the first re-test disappoints.