The kids come out of the water with red, watery eyes. The chlorine smell is strong, almost harsh. The natural reflex is to think “there’s too much chlorine in my pool.” The idea is so widespread that it has come to be accepted as fact. Yet it’s false.
Stinging eyes, tight skin, the intense smell of “chlorine”: these three discomforts don’t come from an excess of chlorine, but from a pH imbalance and a buildup of chloramines. These by-products form when chlorine comes into contact with sweat, urine, sunscreen oils and the other residues left behind by swimmers. Here’s how to decode these signals your water is sending you.
A persistent myth: “it stings because there’s too much chlorine”
Well-chlorinated water, at 1-3 ppm of free chlorine, doesn’t sting the eyes. The proof: public pools, generally heavily chlorinated but well balanced, don’t irritate swimmers. What causes the discomfort is almost always:
- An unbalanced pH (too acidic or too basic)
- A buildup of chloramines (combined chlorine that no longer disinfects)
- Water saturated with organic matter that chlorine struggles to oxidize
In other words: it isn’t the chlorine itself that irritates, it’s what remains once it has done its job.
Stinging eyes: what it really reveals
The natural pH of the eye is around 7.4: exactly the target in a well-balanced pool. As soon as the water’s pH moves away from this value, especially downward (acidic water), the eyes react immediately.
Quick diagnosis:
| Symptom | Probable cause | Adjustment |
| Red, watery eyes | Low pH (< 7.2) or chloramines | Test pH and combined chlorine |
| Mild stinging | pH slightly out of range | Adjust pH toward 7.4 |
| Intense burning | High chloramines + low pH | Shock treatment + pH adjustment |
Strong chlorine smell: a sign of *combined* chlorine, not an excess of chlorine
The smell you associate with “too much chlorine” is in fact that of chloramines, or combined chlorine. These are the residues of chlorine that has already reacted with sweat, urine and the other matter swimmers leave in the water: it gives off a pungent smell, but it no longer disinfects. The stronger the smell, the more combined chlorine there is, and so the less your water is actually protected.
The right indicator: your test should measure total chlorine and free chlorine. The difference between the two gives the combined chlorine. If it exceeds 0.5 ppm, a shock treatment is in order. According to Health Canada recommendations, combined chlorine should stay under 0.4 ppm in a well-maintained pool.
Dry skin, itching: unbalanced pH
Skin that feels tight after swimming, mild itching, hair that feels “rough” to the touch: these signals almost always point to a pH out of balance. Water that is too basic (pH > 7.8) leaves mineral deposits on the skin and hair, while water that is too acidic (pH < 7.2) irritates and weakens the skin.
Bringing the pH back to 7.4 usually solves the problem within a few hours, the time it takes for filtration to distribute the correction throughout the pool.
How to test your water and correct course
Here is the minimum to measure each week, and more often during a heat wave (see our article on heat waves and pool water) :
- pH: between 7.2 and 7.6
- Free chlorine: between 1 and 3 ppm
- Total chlorine: if the gap with free chlorine exceeds 0.5 ppm, perform a shock treatment
- Total alkalinity: between 80 and 120 ppm to stabilize the pH
A liquid test kit gives more accurate results than test strips for pH and chlorine. For the other parameters (calcium, stabilizer), a test performed by a professional twice a season is enough.
When the discomfort signals a larger problem
If the discomfort persists despite adjusting the pH and a shock treatment, the problem goes beyond water chemistry. Three avenues then deserve to be explored:
- Insufficient filtration: saturated sand, a cartridge at the end of its life, flow that is too low
- A dropping water level: a leak can cause the parameters to vary continuously
- A failing salt system: a cell at the end of its life produces less chlorine, which throws all the parameters out of balance
“The myth of ‘too much chlorine’ is what makes us sell the fewest interventions. When we explain that what stings is the chloramines, and that we fix it with a properly dosed shock treatment, people quickly understand they don’t have a product problem, but a routine problem.”
– Tristan Dufour, owner and pool expert, Piscine Évolution
Water that’s pleasant for the whole family.
When the water stings, it’s not the fault of a missing product: it’s rather a balance that has broken. If you don’t feel like playing apprentice chemist over the weekend, our weekly maintenance team monitors these parameters, adjusts them before the situation gets complicated and keeps your pool water pleasant for your children and your guests. Request an estimate for a diagnostic or weekly maintenance, and enjoy water that won’t make anyone cry anymore.
Frequently asked questions
Sweat, sunscreen oils, urine and the other residues brought in by swimmers react with chlorine and create chloramines. The more swimmers there are, the more likely the discomfort is to appear. A shock treatment the day after heavy use prevents the problem.
No. A saltwater pool produces chlorine by electrolysis, and the same rules apply: it’s the pH and the chloramines that cause the discomfort, not the disinfection method.
Yes. A quick shower removes the residues deposited on the skin and limits dryness, especially in children with sensitive skin.
