Chlorine smell in pool

[poolsam]

The other night we were at a hotel chain with indoor pool. As we entered the pool area we were welcomed with the intense smell of chlorine. I realize this is not chlorine, but rather chloramines resulting from chlorine mixing with sweat, urine, and bacteria. The concern I gather is the risk of fee chlorine being low if not replenished by management. The pool obviously needs to be shocked to oxidize the chloramines.

Then I got confused. Can you fix this smell simply by adding more chlorine? Why is it rare to have to shock an outdoor SWG pool? The same urine, sweat and bacteria must become chloramines. What happens to the chloramines?

Next trip just for fun I'll bring my test kit when I encounter that strong chlorine smell.

 

[svenpup]

Q1: yes. You can fix it with more chlorine.

It is funny that people are so quick to think that smell is too much chlorine. I am sure that my guests would be shocked that my FC is 7 when they say things like I love your salt pool with no chlorine.

Q2: this has been done before. I think it was Richard. Typically high Cya and barely any FC.

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[poolsam]

How does the outdoor pool with a SWG get by often without the need for shocking. How do the chloramines get eliminated by the high chlorine shock? Do they get oxidized and the bacteria / protein particles wind up in the filter?

 

[Smykowski]

"Shocking" is a term bandied about by the pool store to solve improper chemical management. Any chlorine pool, SWG or otherwise, never needs to be "shocked" if the chlorine level is always maintained at an appropriate level in the first place. ( I haven't shocked my pool in 3 years, and don't plan to anytime soon.)

Chloramines are the first byproduct of free chlorine oxidizing bather waste and other nitrogen based compounds. In a clean outdoor pool, there will be miniscule amounts of chloramines present from bather waste, but its so little, sunlight quickly oxidizes it.

In an indoor pool, sunlight isn't available, and if the chloramine level gets too high, more free chlorine will oxidize it (eventually).

 

[chem geek]

The bather load is also much lower in a typical residential pool than in a commercial/public pool. You do get chloramines in your outdoor residential pool as well (some are intermediates that get further oxidized by chlorine), but the bather load is so low that the amount is very small and barely detectable (<= 0.2 ppm CC). The sunlight also breaks down chlorine producing hydroxyl radicals that are powerful oxidizers and the sunlight also directly breaks down dichloramine. Also, you usually have some breeze or wind outdoors at least part of the time and that blows away any accumulation of chloramine gasses in the air above the pool. Finally, some indoor pools don't use any CYA so the active chlorine level is higher and this tends to produce more of the most volatile and irritating chloramine, nitrogen trichloride (aka trichloramine).

Nevertheless, if you visit an indoor pool that has a strong smell, it's probably not being properly maintained (including proper air circulation in the room).