Walk past almost any public pool and you'll get hit with that sharp chemical smell. Most people call it "chlorine smell" and assume the pool is over-chlorinated. Pool operators get complaints about it constantly. And almost every time, the problem is actually the opposite of what people think.
The Most Common Pool Myth
A strong "chlorine" smell means the pool has too much chlorine. In reality, that smell is chloramines — a byproduct that forms when chlorine is used up reacting with organic compounds. A pool that smells strongly of chlorine is usually a pool with insufficient free chlorine left to do its job.
What Chloramines Actually Are
When chlorine is added to pool water, it works in two forms. Free chlorine (FC) is the active sanitizer — it's what kills bacteria, oxidizes organics, and keeps the water safe. Combined chlorine (CC), also called chloramines, forms when free chlorine reacts with nitrogen-containing compounds: ammonia from sweat, urine, sunscreen, and body oils that swimmers bring in.
Chloramines are the spent, used-up form of chlorine. They smell bad, irritate eyes and skin, and provide almost no sanitizing ability. When a pool smells strongly, it's because the ratio of combined chlorine to free chlorine is high — meaning a lot of chlorine has been consumed and converted to a byproduct, with little active chlorine remaining.
A well-maintained pool with proper free chlorine levels is nearly odorless. The absence of smell is actually the sign of good chemistry.
Why Your Eyes Burn in Pools
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Get a Free Quote →Same mechanism. Eyes burning in a pool is almost always a chloramine issue — not excess chlorine. When someone says "the chlorine is burning my eyes," the actual fix is better chlorine management, not less chlorine. This surprises most people, but it's consistent chemistry.
What Causes Chloramine Buildup
High Bather Load Without Enough Chlorine Reserve
Every person in a pool introduces organic compounds — sweat, sunscreen, body oils — that consume chlorine and produce chloramines. A pool with 10 people in it on a hot Saturday afternoon is consuming chlorine faster than a pool sitting empty. If the chlorine reserve isn't high enough to handle that load, chloramines accumulate fast. This is why public pools during peak hours often smell the worst.
High CYA Reducing Chlorine Effectiveness
Cyanuric acid (CYA) stabilizes chlorine against UV degradation, which is necessary in SoCal's sun. But when CYA climbs too high — above 80 to 100 ppm — it binds a significant percentage of the chlorine in the water, making it unavailable for sanitizing. The water tests positive for chlorine but much of it is effectively inactive. Organic compounds still react with whatever free chlorine is available, producing chloramines, while the pool appears to "have chlorine" on paper. High CYA situations require a partial drain to dilute it.
Insufficient Shocking
Breakpoint chlorination — shocking the pool — is the process of adding enough chlorine at once to oxidize and destroy chloramines. The breakpoint is the concentration at which combined chlorine is fully oxidized. If you're not reaching breakpoint when you shock, you're not clearing the chloramines — you're just adding more chlorine that will also eventually become chloramines. The fix is a proper shock dose, not a token amount.
How We Prevent It
Enzyme pre-treatments break down oils, sunscreen, and organic compounds before they can react with chlorine and form chloramines. We use these weekly as part of our standard chemical regimen — it reduces the organic load on the chlorine system and keeps the water cleaner at a molecular level. Combined with proper CYA management and shock treatment after heavy use events, chloramine buildup stays under control.
Salt chlorine systems also tend to have less chloramine odor because the electrolytic process generates chlorine continuously at lower, steadier levels — rather than the spike-and-drop cycle of manual chlorination, which creates windows where chloramine buildup accelerates.
💡 After heavy pool use — a party, a hot week with daily swimming, heavy rain — shock the pool that evening or the next morning. This is the single most effective thing you can do to prevent chloramine accumulation after a high-load period.
We handle the chemistry on every visit so you don't have to think about it. See what that looks like in practice on our weekly service page, or read about phosphates — another chemistry issue specific to SoCal pools that we manage proactively.