Real-life case: the pH that climbed back up every three days
- The situation: pH brought back into range every Monday, climbing to 7.8+ by Thursday — an endless yo-yo.
- The hidden cause: alkalinity (TAC) too high, making the pH unstable and 'springy' after every correction.
- Fixing the alkalinity first stabilises the pH: you correct the foundation, not the symptom.
- Bonus: aeration (waterfall, jets) and salt electrolysis also push the pH upwards.
Monday: pH brought back to 7.2, perfect. Thursday: already 7.8. Re-correction. The following Monday: same again. The pH yo-yo is one of the most frustrating bits of maintenance there is — you feel like you’re emptying bottles of pH minus into a bottomless pit, never stabilising the water. On this pool, the culprit wasn’t the pH itself. It was the number nobody ever looked at: the alkalinity (TAC).
The pH is only the symptom
Here’s the mechanism nobody explains to the beginner. The pH doesn’t float on its own: it’s “held” by the alkalinity (TAC, the buffering power of the water). Alkalinity acts like a spring: when it’s in range, it stabilises the pH and corrections hold. When it’s too high, that spring is too stiff — it pulls the pH back up after every correction, and you replay the same game every three days. Correcting the pH without touching the alkalinity is like pressing on a compressed spring: it bounces back.
The full test showed it clearly: alkalinity well above its range. The pH wasn’t “rising” on a whim — it was being mechanically pulled upwards, again and again.
The correction that changed everything
The plan reversed the order of priorities: alkalinity first. Lowered gradually towards its target range — in calculated steps, because correcting alkalinity transiently affects the pH and takes a careful hand. Once the alkalinity was stabilised, the pH settled on its own: Monday’s correction held until the following Monday, then beyond. The bottle of pH minus, until then emptied every week, lasted a month.
Two aggravating factors were also identified and taken into account. Aeration: the decorative waterfall, pretty but running constantly, was off-gassing CO2 and pushing the pH up — they ran it less. And for the pools concerned, salt electrolysis structurally raises the pH: a permanent point to watch, not a bug.
Peace of mind restored
The lesson transformed the routine: they no longer “chase the pH”. They monitor the pH + alkalinity pair by photo, the app keeps the history and shows the foundation is holding. When the pH moves now, it’s slowly and predictably — not in three days. The water, as a result, is stable across the board: the chlorine works at full power (a stable in-range pH keeps it active), the water no longer clouds, the waterline no longer scales.
What this case teaches
A pH that keeps rising is almost never a pH problem: it’s an alkalinity problem. As long as you treat the symptom, you’re doomed to the yo-yo and the endless bottles. Fixing the foundation — alkalinity in its range — makes pH corrections last, and frees up huge amounts of time. The app always looks at the pH/alkalinity pair together, calculates the corrections in the right order (alkalinity before pH) and with the right dosing, and warns you when the foundation moves. No more chasing a moving target.
Frequently asked questions
Why does my pH keep rising despite the pH minus?
Most often because of total alkalinity (TAC) that's too high: it acts like a 'spring' that pulls the pH back up after every correction. Until you bring the alkalinity into its range, you treat the symptom in a loop. Aerating the water and salt electrolysis make the rise even worse.
Should I correct the alkalinity or the pH first?
Alkalinity first: it governs the stability of the pH. Alkalinity in range makes pH corrections last; alkalinity out of range makes the pH a moving target, whatever product you use.
Is a rising pH serious?
Short term, no, but a persistently high pH deactivates the chlorine (water that can turn despite good numbers), clouds the water and causes scale in hard-water areas. Stabilising it secures everything else in your maintenance.