On Tuesday, something happened to the diving pool at the Rio Olympics. It turned green. Not just a little green. No. This was full-on lime Jell-O green, close to the color swatch movie set designers turn to when they want to make something look radioactive. 
 
 As of Friday, the pool is closed — and as a correspondent for the Today Show noted, the issue isn't limited to the water: 
 
 The Olympic diving pool has been closed again because of water quality issues...a German diver says "the whole building smells like a fart" — Tom Steinfort (@tomsteinfort) August 12, 2016 
 
 At first, Rio Olympics attributed the green color to "a proliferation of algae." Mario Andrada, a Rio spokesperson, told the Associated Press, "We did all the chemical tests." 
 
 And it appears the green discoloration is affecting another pool (used by water polo players and synchronized swimmers) at the outdoor aquatic center. 
 
 What happened? The Los Angeles Times talked to a spokesperson at the International Swimming Federation, or FINA, swimming's international governing body. According to FINA, the green color is not due to an algal bloom but to a problem with the pools' pH after the aquatic center ran out of the chemicals to fix it. Here's FINA's statement. 
 
 FINA can confirm that the reason for the unusual water color observed during the Rio diving competitions is that the water tanks ran out of some of the chemicals used in the water treatment process. As a result, the pH level of the water was outside the usual range, causing the discoloration. The FINA Sport Medicine Committee conducted tests on the water quality and concluded that there was no risk to the health and safety of the athletes, and no reason for the competition to be affected. 
 
 Did you catch that? Apparently, not enough pool chemicals were stocked for the Olympics. 
 
 Andrada told the New York Times that the pools' pH was thrown off by the large numbers of people using the pools. "We probably failed to note that with more athletes, the water could be affected," Andrada told the paper. "The people in charge of the pool should have done more intensive tests." 
 
 One other question: How does a change in pH change the color of the water? 
 
 I talked to Nate Hernandez, director of aquatic solutions at VivoAquatics, a company that builds and maintains pools in resorts and public facilities across the country. 
 
 He suggested a couple of ways. 
 
 One: A low or high pH can bring out minerals. "Calcium would show itself as cloudy water, copper would show up as a blue-green," he says. 
 
 Two: A too-high pH would render the chlorine ineffective, which could then allow for the proliferation of algae. (Hernandez says it's doubtful, though, that the green color is mainly from algae. It typically doesn't bloom that fast in such large pools.) 
 
 Hernandez is also a bit baffled as to how this could have happened. The Olympic officials ought to have known how many athletes would use the pools. And these pool control systems are largely automated. "Multiple things would have had to break down for this to happen," he says. "There's a lot of chatter going on in the aquatic industry about this." 
 
 I asked Hernandez if he'd be embarrassed if this were one of his pools. 
 
 "I'd be fired," he replied. 
 
 As Vox's Libby Nelson explained, it was the water quality in Rio's waterways that had people worried before the games began: 
 
 The pollution in Rio's waterways is serious: The locations for the rowing and sailing races are ridden with viruses that could sicken athletes if they inadvertently end up swallowing water, according to an investigation from the Associated Press. Five times in the past 13 months, Copacabana Beach, where the marathon swimming and triathlon will take place, had so much rotavirus in the water that if it were located in California, it would have had to post water quality warnings. 
 
 No one thought the swimming and diving pools would pose a problem. And perhaps it’s not a big deal, considering the officials say it’s safe. But the bigger question is: If it’s not resolved soon, would athletes be willing to compete in it? 
 
 Watch: Simone Biles is the gymnastics gold standard ||||| Canada's Meaghan Benfeito, top, and Roseline Filion compete during the women's synchronized 10-meter platform diving final in the Maria Lenk Aquatic Center at the 2016 Summer Olympics in Rio de Janeiro,... (Associated Press) 
 
 Canada's Meaghan Benfeito, top, and Roseline Filion compete during the women's synchronized 10-meter platform diving final in the Maria Lenk Aquatic Center at the 2016 Summer Olympics in Rio de Janeiro, Brazil, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham) (Associated Press) 
 
 RIO DE JANEIRO (AP) — Green, not gold, was the color of the day at the Olympic diving venue. 
 
 Sure, China won its third consecutive gold medal on Tuesday, but the buzz was about the color of the water in the diving pool — a murky green. 
 
 That was in stark contrast to the pool's light blue color the previous day and also that of the clear water in the second pool used for the water polo competition at Maria Lenk Aquatic Center. 
 
 British diver Tom Daley, who earned bronze in men's synchronized 10-meter on Monday, tweeted a photo of the two pools next to each other and captioned it, "Ermmm...what happened?!" 
 
 Water quality has been a major issue surrounding the Rio de Janeiro Olympics, but in the ocean and lagoons, not the pools. 
 
 A statement from Olympic organizers said water tests were conducted and there was no risk to athletes. They couldn't explain the color change, but said it's being investigated. 
 
 Rio spokesman Mario Andrada said the green was caused "by a proliferation of algae." 
 
 "This was because of heat and a lack of wind," he said. "We did all the chemical tests. The pool will be blue tomorrow (Wednesday). 
 
 "If it were green and yellow, we would know it was a patriotic thing," Andrada joked, referring to Brazil's national colors. 
 
 Canada team leader Mitch Geller suspected the cause was algae that multiplied quickly in the day's warm and sunny conditions. 
 
 "Everybody was scratching their heads going, 'What's going on?'" he said. "I think that the filter is busted, but I'm not sure. It's not really dangerous. It's not like it's toxic or dirty or any of that. It seemed to get worse over the course of the competition." 
 
 The kale-colored water wasn't just a cosmetic nuisance; it was so dark that divers couldn't see the bottom of the pool. 
 
 "They're used to seeing the water," Geller said. "The visuals are really, really important in diving." 
 
 Chen Ruolin, who teamed to win gold with Liu Huixia, said it didn't affect them. 
 
 Paola Espinosa of Mexico, competing in her fourth Olympics, noticed the pool getting increasingly darker throughout the six-round competition. But she said the water didn't smell or affect her skin. 
 
 "I haven't seen anything like it before," Espinosa said. "But it's Brazil and everything is green down here, so maybe it was a decoration to make it look pretty." 
 
 American Jessica Parratto wears contacts and said the water didn't burn her eyes. 
 
 Bronze medalists Meaghan Benfeito and Roseline Filion of Canada tried not to laugh as they gazed at the water from atop the 33-foot tower. They liked that the dark green color offered a helpful contrast with the blue sky. 
 
 "The only thing we said is don't open your mouth in the water, just in case," Benfeito said. 
 
 Geller said a Canadian pool expert was coming in Wednesday and he would offer to help Rio organizers chemically treat the water if there's a problem with the filter. 
 
 "I don't know what it's going to look like tomorrow," he said. "I hope it's not a swamp." 
 
 ___ 
 
 Associated Press Writers Carlos Rodriguez and Stephen Wade contributed to this report.
– If you happened to tune into a diving event Tuesday, you probably noticed the pool at Rio's outdoor aquatics center was "as green as split-pea soup," as the National Post puts it—or "close to the color swatch movie set designers turn to when they want to make something look radioactive," per Vox. Indeed, just a day earlier the outdoor pool had appeared crystal clear. Vox floated several theories, including an insane amount of urine in the pool, or perhaps a corroding pipe. (BuzzFeed also rounds up theories and reaction.) An official statement from Rio's organizing committee said the cause was under investigation, though a spokesman late Tuesday chalked it up to a "proliferation of algae" whipped up by "heat and a lack of wind," reports the AP. "it will be blue from now on," he promised. But as an image at Gizmodo shows, the problem appears to have shown up Wednesday in the neighboring water polo pool. Officials had previously said the green water posed no danger to athletes, and one half of Canada's women’s synchronized diving pair, who won bronze on the 10-meter platform Tuesday, certainly didn't mind. "[Diving] is a visual sport and you have to see the water," Meaghan Benfeito tells the Post. "The fact that it was completely different from the sky really helped us." (Team USA won multiple gold medals in a separate pool Tuesday.)