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Wrong Chemical Dumped Into Olympic Pools Made Them Green (arstechnica.com)
Z00L00K writes: [Ars Technica reports:] "After a week of trying to part with green tides in two outdoor swimming pools, Olympic officials over the weekend wrung out a fresh mea culpa and yet another explanation -- neither of which were comforting. According to officials, a local pool-maintenance worker mistakenly added 160 liters of hydrogen peroxide to the waters on August 5, which partially neutralized the chlorine used for disinfection. With chlorine disarmed, the officials said that 'organic compounds' -- i.e. algae and other microbes -- were able to grow and turn the water a murky green in the subsequent days. The revelation appears to contradict officials' previous assurances that despite the emerald hue, which first appeared Tuesday, the waters were safe." I would personally have avoided using the green pools, but that's just me. "Hydrogen peroxide is sometimes used in pools -- often to de-chlorinate them," reports Ars. "Basically, the chemical, a common household disinfectant, is a weak acid that reacts with chlorine and chlorine-containing compounds to release oxygen and form other chlorine-containing compounds. Those may not be good at disinfecting pools, but they still may be picked up by monitoring systems. Hydrogen peroxide can also be used to disinfect pools but must be maintained in the waters -- not a one-time dumping -- and can't be used in combination with chlorine." Apparently, the green water irritates eyes and smells like farts.
Just happened to have 100+ gallons of hydrogen peroxide sitting around.
More likely, they tried to be clever and use it in an attempt to sanitize the pool after a test for high bacterial load.
Since the "officials" had no knowledge of how the pool was treated, they cannot offer assurances that it's "safe." They just don't know.
Dumping in a lot of chlorine is not sufficient to sanitize a pool. The PH also needs to be in the proper range (7.2 - 7.8). The water also needs to be pumped through the filter for 8 - 12 hours a day (24 if cleaning up a green pool). The surfaces of the pool need to be brushed to move dead algae from the pool surface into the water (after which the filter will catch it).
Partly.
The "chlorine" smell in pools is from Chloramines - a compound made of chorine and amines (ammonia). You get more of it from urine, but it'll build up anyway from other sources. The Chloramines are also what stings and irritates the eyes, nose, and lungs.
How do you get rid of it? Raise the free chlorine level in the pool to 10 ppm or so (normal range is 1 - 3 ppm). Presto, changeo, the pool stops smelling like chlorine.
Cryptosporidium is a difficult to remove parasite that can exist in pool water. How do you treat pool water that's been contaminated with crypto? Raise the chlorine level to 10 ppm for 24 hours (20 ppm if you use stabilized chlorine).
Me? I just keep my pool between 10-20 ppm chlorine all the time. Crystal clear water, no algae, no eye irritation, no chlorine smell, no nasties in the water, no side effects at all. My kids swim in it eyes wide open for hours at a time, friends come over and say "I'm glad you don't use too much chlorine; I can't even smell it".
And the worms ate into his brain.
Ok, I'll plow into this.
Pool chemistry is, well, chemistry. And despite the offhand IOC statement that "chemistry is not an exact science", chemistry is science. And it's an excellent topic for /.
Maintaining my little 10,000 gallon play pool has been an interesting adventure;
- In Arizona, sunlight and temperature conspire to make pool maintenance a challenge; sunlight by itself both encourages everything you don't want in your pool (algae and bacteria for two) and decomposes chlorine, your most common disinfectant and algaecide.
- Cyanuric Acid (CYA), used as a chlorine stabilizer, also binds chlorine so that it is ineffective as a disinfectant etc. And it does not, itself, decompose easily or quickly. CYA is used in residential pools to simplify management (intermittent filtering and circulation mean chlorine levels would fluctuate without stablizer) and to reduce cost (burnt off chlorine requires adding more). Commercial pools don't typically need this, and indoor pools even less.
- Chlorine tablets (most commonly Trichloro-S-Triazinetrione) and much granulated chlorine (commonly Calcium Hypochlorite, so-called 'shock') contain CYA, and each bit you use adds CYA to your pool, eventually increasing the concentration to the point that it renders chlorine ineffective.
- Now you get to increase the amount of chlorine you use, also increasing the CYA, and the effect compounds itself.
- The solution is to drain the pool, reducing the concentrations, and add your chlorine sources to restore the level, starting the cycle again. Yes, you do.
- I now use an erosion dispenser that doesn't float, and it works insanely well. CYA levels of 110ppm force my free chlorine levels to test 1ppm, but the pool is clear and free of algae and detectable contaminants.
- Commercial and Olympic pools would never use erosion dispensers. I expect them to use gas systems. And using CYA is wrong for these pools because they should be constantly dispensed, constantly monitored, and chlorine expense is
So my challenges are different than those at the Games, but similar in some details.
I tried liquid chlorine (Sodium Hypochlorate, Clorox without the perfume and higher concentrate) for a while, but it's not as effective and requires constantly measuring and pouring, whereas tablets dissolve (erode, hence those floaters called erosion dispensers) without intervention or attention beyond filling it when they are gone. I gave that up without buying or trying to build an automated dispenser, just not worth it yet.
The problem at the Olympics has been well discussed, but from my view as a residential pool owner:
0. They let the chemistry get out of hand. I expect such a pool, at such an event, to be constantly monitored. Inexcusable.
1. Having let it get out of hand, a proper shock by adjusting the pH and alkalinity, using, for instance, a disodiumsalt of ethylenediaminetetraaceticaciddihydratediammoniumsulfate (this is a proprietary product that works), then Calcium Hypochlorate or other chlorine should have cleared the pool overnight. It does mine, even in 90 overnight temps, the only difference being quantities. A filter aid would clear the milky residue that we saw on TV. This process can be used to successfully clear a pool in 12 hours.
2. Using Hydrogen Peroxide wasn't just a mistake, it was malpractice, and I would fire the nimrod that decided that. It is incompatible with chlorine, period. Huge mistake.
3. the filters should be running constantly, not because of demand but because of the critical nature of maintenance. These are used throughout most of the day, are critical to the Games, and no excuses. Similarly the disinfectant systems. It's not about the cost, it's about the money.
4. Each pool should have had its own filtration and disinfectant systems. Of course.
I give the maintenance teams a grade of F. Just incompetent in these pools, and no such failure is acceptable.
deleting the extra space after periods so i can stay relevant, yeah.