The Olympic swimming pools have become the talk of the games so far. Whether it’s Michael Phelps still dazzling us with gold medal victories, Katie Ledecky trouncing her competition or, yes, pools turning green.

How does this happen?

After the pool used for diving turned green, a second pool, used for water polo, changed color Wednesday.

But we now know why, according to the New York Times.

“Midafternoon, there was a sudden decrease in the alkalinity of in the diving pool, and that’s the main reason the color changed,” Mario Andrada, a Rio spokesman, said Wednesday. “The people in charge of the pool should have done more intensive tests. We brought in a team of independent experts to check.”

So, to go along with the theme of the Olympics, preparation doesn’t seem to be a key factor so far. When the reason for the pools turning green is having too many people/athletes in them, something is wrong. It seems fairly easy to estimate how many people would be in the pool each day based on the number of events.

The good news, however, is there is no health risk to the athletes with this Jell-O-like color in the pool now.