Many of you, looking at this pond, would think: “Wow, that's what I dreamed of as a child!”. And then they would have jumped down and probably drowned - because there is a lot of water under the balls. To be exact - 12.5 million liters. This artificial pond is a source of drinking water for many Los Angeles residents. Including for Derek Muller, who is conducting a strange experiment here. If you think about why you need to close all the water with balls, then the answer seems obvious and lying on the surface - protection against evaporation. But there is another, less obvious reason to use balls.
Bromides, hydrobromic acid salts HBr, can get into the tank along with the salt water. By themselves, they do not harm humans, but when drinking water is treated with ozone, they are converted into bromates, the salts of bromic acid HBrO3, which are carcinogenic.
A study of the situation showed that bromates in the reservoir are formed even before ozone treatment. And the reason for this - the interaction of bromides and chlorine compounds under the influence of sunlight. And, as you already understood, 96 million black balls perfectly protect city residents from the formation of harmful substances. “This has eliminated the problem completely,” say the local water and energy department.