If you've seen pictures of the Los Angeles reservoir (LA) covered by millions of black plastic balls, you may wonder two things: What are they? And can you swim on it?
Plastic balls are released on Lake Los Angeles to prevent water evaporation from the lake
Derek from the Veritasium YouTube channel recently had answers for many people through a video that attracted more than 33 million views. In fact, 95 million plastic balls cover the entire lake of LA to prevent evaporation and keep water for the lake.
Besides the main effect of water retention, this lake also works to solve problems related to bromide, a natural substance found in salt. Bromide itself is harmless to humans but if a part of this chemical flows into a freshwater reservoir for drinking, treated with ozone, it can form a bromide compound and this is a carcinogen.
The Ministry of Water and LA did not expect that the carcinogen soared in the tank turned out to be due to bromide and chlorine interacting with sunlight. This reaction produces more bromide than before without interacting with ozone.
So these balls are placed in the lake to prevent sunlight from coming into contact with the reservoir. Besides, these balls ensure no toxic to lake water below.

The plastic balls are manufactured in the factory
As for the second question, Derek decided to swim on the lake full of super heavy black balls to answer questions for many people about the lake still being able to swim just a little hard.

The guy Derek put the number of balls from the factory and brought it to the surface of the indoor pool
For those who do not know, no one is allowed to swim on the other balls in LA Lake, because this is a source of drinking water. However, to find the answer to the question, Derek tried to persuade those who released the ball to allow him to swim through 10 thousand balls to verify the suspicion.
Of course the authorities will not allow you to swim in this shiny pool of water. That's because they are not like ordinary balls that contain a certain amount of water so they are quite heavy and dangerous.
But for scientific purposes, the authorities agreed to allow Derek to swim through the balls and to show why we should not be in a pool filled with such shadows.


When the first drop, the number of balls is not much, Derek guy can swim easily


Swimming is still very comfortable and there is no difficulty


The first time with a small amount of water, the lake can still swim

But when stocked in large numbers, the guy in the video could no longer swim normally

Getting out of the balls is hard

So it is even more difficult to swim in full water recovery
Accessing the balls was difficult but transporting them to the pool where Derek performed the test was also a difficult journey. The estimated weight of about 1200 balls falls into about 300kg.
The end result is quite interesting and you can see more in the video below:
Dive in a plastic swimming pool
Refer to Sciencealert