Chlorine smell and stinging eyes: the chloramine paradox
Counter-intuitive: a strong chlorine smell and stinging eyes do not mean too much chlorine, but "used-up" chlorine in the form of chloramines. The solution is not to add less, but to run a shock treatment.
In short
The distinctive sharp smell and eye irritation come from chloramines: compounds formed when chlorine reacts with organic residues (sweat, urine, sunscreen). They indicate saturated chlorine, not an excess. You remove them with super-chlorination (shock chlorine), backed up by aeration and good filtration.
Why it smells of chlorine
Free chlorine — the kind that disinfects — is almost odourless. The strong smell comes from chloramines, formed when it combines with organic matter brought in by bathers. The more chloramines, the more it smells "of pool" and the more the eyes sting — a sign the chlorine is overwhelmed, not in excess.
Breaking down chloramines
The right response is super-chlorination: a shock treatment that briefly raises chlorine high enough to destroy the chloramines. Alongside, aerating the water (jets, movement) and strong filtration help eliminate them. A shower before swimming greatly reduces their formation.
What to do, step by step
Test the chlorine and pH
A correct pH (7.0–7.4) is essential for the shock treatment to work.
Carry out a shock treatment
Super-chlorination breaks the chloramines. Swimming is discouraged until the chlorine has come back down.
Aerate and filter
Run filtration and stir the water: chloramines clear out faster.
Prevent a recurrence
Shower before swimming, steady chlorine and sufficient filtration limit chloramines from forming again.
Frequently asked questions
Too much chlorine or not enough?
Not enough available free chlorine, in fact. The smell comes from chloramines, a sign chlorine is saturated with organic matter. A shock treatment, not a reduction, is the answer.
Can you swim when it smells strongly of chlorine?
Better to avoid: the eye and airway irritation come precisely from chloramines. Treat first, then wait for chlorine to return to a normal level.
How do I avoid chloramines?
By requiring a shower before swimming, keeping steady chlorine and suitable filtration, and running a periodic super-chlorination when the pool is busy.