Chlorine and “Red-Eye”
Have you ever been in a pool that made your eyes so bloodshot that you looked like a refugee from a Cheech & Chong movie? Or took a dip in a spa that overwhelmed you with a chlorine odor? A lot of pool owners want to cut down on chlorine usage to avoid some of these issues.
In both of the above examples, though, excess chlorine is not the problem. Let’s take those two common assumptions about chlorine and toss them aside. “Just the facts, ma’am,” as Joe Friday would say.
Red Eye: Too Much Chlorine?
We’ve all been in a pool where, after only ten minutes, your eyes feel like they’re burning. And red? Heck, yes! This is caused by too much chlorine, right?
Wrong. The problem here is that pH of the water is off.
The pH is the acid/base balance of the water. Acids and bases are opposites. A pH of less than 7.0 is acidic, above that is basic.
In a pool, the pH should be 7.4, or very close to that. See, the pH of the surface of your eyes is about 7.4, so if the pool has a pH very far off that, it will irritate your eyes. And, of course, the farther it is from that desired range, the more your eyes hurt.
So, if you keep your pH at 7.4, you can let your chlorine ride high, say 3-5 ppm (national standards are 1 ppm minimum residual of free chlorine at all times). And your eyes will be fine.
Years ago, I did pool maintenance in Rancho Santa Fe, California, which was the richest zip code in the country at the time. Those people would complain about everything — lizard falls in the pool, “Drain it!” Anyway, we let our chlorine levels ride slightly high, but kept the pH right at 7.4, and we never had red-eye complaints.
Ooh-ooh That Smell!
Ever been in a pool, or more commonly, a jacuzzi, and smelled a strong chlorine smell? Quite often, it’s at a public facility, like a hotel or health club.
So, what needs to be done to get rid of that bit of unpleasantness? Well, here’s where another common assumption goes flying out the window–what you need to do is add MORE chlorine.
That’s right: if it smells like chlorine, add more.
See, what you are smelling are “chloramines,” chlorine combined with other stuff, usually nitrogen-containing products. Sunscreen, makeup, sweat, body oil. Icky stuff like that. But probably the most common source of chloramine in a pool or spa comes from urine combining with free chlorine.
Urine? Yeah, ‘fraid so.
And, by the way, that foamy spa at the hotel? The one that looks like somebody added a little soap to it? Yeah: full of chloramines. If you see a spa that looks like a tamer version of a bubble bath, don’t get in it. Or if it smells like chlorine, or even worse, has a locker-room smell, stay out. All of its chlorine is locked up in chloramines, which are much weaker sanitizers than regular free chlorine.
Adding more chlorine breaks the bond between the chlorine and the other compounds. Most of both compounds then gas off, using up the extra chlorine you just added. Once all the chloramines are taken care of, there needs to be some chlorine left over for a residual. That just means there needs to be enough left over in the water to kill any bacteria, algae or viruses that are introduced to the water. This little arcane corner of water chemistry is called “break-point chlorination,” and is a little too technical for us to get into here, though.
Chlorine Ain’t a Bad Thing
So, the point of all this is that chlorine isn’t the source of all the stuff usually blamed on it. Now, it will fade your bathing suit and eat up it’s Lycra and elastic. And it will oxidize some stuff, like leaves or seed from plants, that ends up in the pool; this can stain the the plaster. Like anything else in life, there’s good and there’s bad when it comes to chlorine.
Some people just have a problem with chlorine, maybe a rash or other type of skin irritation. Well, there are alternatives to chlorine, like ozone or Baquacil.
But if you keep your pH close to 7.4 and your levels of free chlorine fairly high, you shouldn’t have any of the smell or eye problems.
