Organizers pledge to transform murky green to crystal clean for synchronized swimmers

Games organizers said they will pump millions of liters of green water from a Rio pool after admitting defeat in attempts to get it back to blue.

In a "radical" step, 3.73 million liters were due to be replaced at the 50-meter water polo pool, which was due to start hosting synchronized swimming on Sunday.

Officials blamed hydrogen peroxide, added to the pool by a contractor, as the reason for the water turning a murky green.

Cleanup efforts were also failing at the nearby diving pool, which was a darker green, according to one diver.

But while the diving pool could remain green without affecting competition, venue manager Gustavo Nascimento said synchronized swimming requires crystal-clear water.

"We've been trying for four days. Obviously it's not going as fast as we wanted ... so we're going to change the water," Nascimento said.

"We're going to drain the water from the competition pool and we're going to pump the water from the warm-up pool into the competition pool."

Nascimento said the operation should be finished four hours before synchronized swimming starts with the duet free routine.

He said the diving pool and then the bigger pool next to it turned green because a contractor added 80 liters of hydrogen peroxide that neutralized the chlorine.

Hydrogen peroxide is used to clean swimming pools, but it should not be mixed with chlorine, Nascimento said.

"Our contractor's failure is our failure," he said, adding that the effect of about 120 competitors jumping into the pool had compounded the problem.

Divers said it had no effect on their performances, but water polo players using the larger pool said their eyes stung as extra chlorine was pumped in.

"Synchronized swimming requires clear water for refereeing and clear water for athletes to see each other, so we're going to change the water," Nascimento said.

"This will be done overnight. The warm-up water is in perfect condition for the athletes to perform at their best."

Games spokesman Mario Andrada said the "radical measure" had been taken after discussions with aquatics body FINA.

Twenty water polo games have been played since the water began to change.

While some players complained of a burning sensation in their eyes, apparently caused by the extra chlorine being added in an attempt to clean the water, no major issues were reported.

"At the end of the day, yeah, the color of the pool may be different or the pH level is whatever it is, but it's a pool," said US women's captain Maggie Steffens.

"If you're a competitor like we all are, if you're here for the right reasons, you're not worried about that. You're worried about playing the game."

Rio officials are also dealing with another mishap at an aquatics venue.

The starting platform for the open water course broke into three pieces during a bout of bad weather, forcing practice to be called off at Fort Copacabana on Saturday.

A backup platform was due to be brought in for the women's 10km race on Monday.

One piece from the shattered platform washed up on Copacabana beach.