One of the biggest myths in pool care is that pH is the most important factor for a healthy pool.
Why do people believe this?
Reason 1: It’s easy to measure. Unlike alkalinity, CYA, or calcium hardness, you only need a test strip to check pH.
Reason 2: It feels logical. Everyone knows that water that’s “too acidic” or “too alkaline” isn’t good for the skin.
Reason 3: It’s what people have been taught. Many pool shops and even technicians focus heavily on pH because it’s simple to explain: “Keep it between 7.2–7.6.” Over time, this advice became the so-called “gold standard.”
Reason 2: It feels logical. Everyone knows that water that’s “too acidic” or “too alkaline” isn’t good for the skin.
Reason 3: It’s what people have been taught. Many pool shops and even technicians focus heavily on pH because it’s simple to explain: “Keep it between 7.2–7.6.” Over time, this advice became the so-called “gold standard.”
So, what’s the problem with this?
1. Good pH doesn’t guarantee good sanitation.
A perfect pH reading doesn’t mean the water is safe. It doesn’t prevent algae, scaling, or chemical imbalance.
2. pH won’t stay put.
Even if you set your pool at 7.4, it’s only temporary. pH naturally drifts upward over time and always tries to return to its “ceiling.”
A perfect pH reading doesn’t mean the water is safe. It doesn’t prevent algae, scaling, or chemical imbalance.
2. pH won’t stay put.
Even if you set your pool at 7.4, it’s only temporary. pH naturally drifts upward over time and always tries to return to its “ceiling.”
Then why do we hear so much about pH?
• It affects sanitation—but only in pools without stabilizer (CYA). Once CYA is in the water, chlorine behavior changes, and CYA becomes the real driver of sanitation, not pH.
• It influences corrosion and scale formation—but not on its own. It’s just one piece of the puzzle. To understand scale or corrosion, you need to look at the overall balance (LSI).
• It plays a role in swimming comfort—but not as much as people think. Studies show that tear and eye pH vary throughout the day and from person to person. Meanwhile, bottled water can range from 5.5 to 9.5 pH—and we drink them all without noticing much difference.
• It influences corrosion and scale formation—but not on its own. It’s just one piece of the puzzle. To understand scale or corrosion, you need to look at the overall balance (LSI).
• It plays a role in swimming comfort—but not as much as people think. Studies show that tear and eye pH vary throughout the day and from person to person. Meanwhile, bottled water can range from 5.5 to 9.5 pH—and we drink them all without noticing much difference.
The bigger picture
We’re not saying you should keep your pool at a pH of 5.5 or 9.5—that would be unsafe. But it’s important to know that, thanks to Henry’s Law, pool water naturally wants to rise toward 8.0–8.2.
If you’re worried about irritation, don’t just obsess over pH. Check your chlorine and chloramine levels. These are usually the real culprits behind red eyes and discomfort, not small shifts in pH.
In short: pH matters—but it’s not the full story. A healthy pool depends on the full balance of water chemistry, not just one number.
If you’re worried about irritation, don’t just obsess over pH. Check your chlorine and chloramine levels. These are usually the real culprits behind red eyes and discomfort, not small shifts in pH.
In short: pH matters—but it’s not the full story. A healthy pool depends on the full balance of water chemistry, not just one number.