Crafts & DIY
Man shows how to make “liquid sand” hot tub by pumping air into it
This guy looks like he's having way too much fun and now I have to try it.
Kate Miano
09.07.21

Have you ever had a crazy idea you thought might just pay off? Have you ever wanted to reinvent the hot tub?

Mark Rober can say yes to both of you, and lucky for us, he’s willing to share his tips.

Turns out that adding air can change sand a lot.

In his video, Mark starts out with a box filled with plain sand. But when he adds air pressure to the box it changes before your eyes.

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

Mark calls it “liquid soup” which is a good descriptor honestly. Using his experience with this small box of sand, he decided to test it out at a larger scale, in a hot tub.

If you want to make this yourself, start with the piping.

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

First, get PVC pipes that are a half-inch thick. Then, drill a bunch of small holes along two sides of the pipes, the two sides should be about 90 degrees apart.

You’re going to arrange your PVC pipes in a ladder formation and glue them all together and place them inside a plastic bin.

Then, add sand and get an air compressor.

The best is refined sand or glass. You want your sand to be pretty smooth and lightweight.

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

To power this contraption, get an electric air compressor that can blow air into the box.

With all those parts connected and fired up, you should be able to play around with liquid sand in no time.

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

But Mark didn’t stop there. He upped the scale.

Mark was curious how it would feel if he used a hot tub instead of a plastic box. Fortunately, one of his friends happened to have one lying around.

He and his friends poured a bunch of sand into the hot tub and hooked it up so that a person can fit inside this fluidized bed.

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

They had a lot of fun playing around with it and even Mark’s nephews were able to enjoy it!

There is some science behind this.

This meeting of sand and air creates what is called a “fluidized bed.” That’s when two parts, liquid, and solid particles, come together.

It’s used sometimes in industrial settings.

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

Because of how fluidization works, many objects often end up hanging in equilibrium when placed under these circumstances.

Two equal forces (gravity and air) are acting upon it, so it kinds just hovers there and feels lightweight. Mark gives a really good explanation of the science and all the forces at play in the video.

Regardless of how well you understand science, people agree that the experiment is awesome.

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

As of today, his video has over 91 million views and 1.4 million likes. The comments section is filled with people admiring the engineering and science lessons.

One person writes:

“OMG I wish I had a science teacher like you growing up. Would have changed everything. I finally understand why balloons float up until a point in the atmosphere.”

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

Someone else says:

“So when my teacher said it was confusing when she was talking about deserts being oceans this is what she meant”

We can all appreciate a cool science experiment.

YouTube Screenshot - Mark Rober
Source:
YouTube Screenshot - Mark Rober

Thanks to Mark Rober for showing us all how this is done! Did he inspire you? If so, you should definitely try to make this at home.

Homemade science experiments are always a fun way to learn more and have a good time.

Learn more about the science behind this and see the fun for yourself in the video below!

Please SHARE this with your friends and family.

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By Kate Miano
hi@sbly.com
Kate Miano is a contributor at SBLY Media.
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