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Published 2:41 PM EDT, Wed August 10, 2016
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General view of the diving pool at Maria Lenk Aquatics Centre on day 4 of the Rio 2016 Olympic Games on August 9.
A 2nd Olympic pool in Rio turns green
01:12 - Source: CNN

Story highlights

Algae to blame for green hue of Olympic pool

Or is it alkalinity?

Rio CNN  — 

There’s something in the water at the Rio Olympics: Yet another pool has turned deep, bright green.

This time, it’s the water polo pool.

On Tuesday, when the diving pool at the Maria Lenk Aquatics Centre mysteriously changed colors, Olympic organizers and FINA – swimming’s international governing body – offered competing explanations why.

The water of the diving pool at right appears a murky green as the water polo pool at left appears a greener colour than the previous day.
The water of the diving pool at right appears a murky green as the water polo pool at left appears a greener colour than the previous day.
Matt Dunham/AP

On Wednesday, the water polo pool at the center also went green.

An inspector takes a sample from the water polo pool which turned green in color.
An inspector takes a sample from the water polo pool which turned green in color.
Matt Dunham/AP

Swimming pools, in case anyone is unclear, are supposed to be a shade of azure.

So, what is going on? There are many explanations.

A change in alkalinity:

Mario Andrada, the communication director for the Rio 2016 local organizing committee, says a sudden change in alkalinity is the culprit.

“We expect the color to be back to blue soon,” Andrada said, adding there is “absolutely no risk to the athletes or anybody.”

An algae bloom:

Nope, the green tone seen was due to a proliferation of algae, the organizing body said. The algae bloomed because of heat and lack of wind, it said.

Poor organization:

Nope, says, FINA, the blames lies with the organizers. FINA claims water tanks “ran out some of the chemicals used in the water treatment process.” It made no mention of wind or heat.

Follow Tuesday’s action with CNN’s Olympics live blog

The Internet dives in

It didn’t take long for the Internet to offer up its own imaginative take on the green shade.

Commenters joked that it was nice of Shrek to loan his swamp to the Olympics, while others shared pictures of Kermit the frog and swamp monsters.

CNN’s Julia Jones contributed to this report.