It has nothing to do with how pools work...

It's about how visible wavelengths work...

Edit:

To actually explain it, red wavelengths are shit at going thru water

Send light to the bottom of a pool and it reflects back as just blue off white.

Send it to the bottom of even a shallow pool that's dark blue, and you get back black. Which warms the water and helps algae. With the green algae, you get even blacker water.

we have two MAGAs in our neighborhood. only one is stupid enough to advertise it constantly. one was stupid enough to put it on his truck around the last election and his house and truck got egged.

when the dude whose house got egged put in a pool, the workers took four months for a simple inground pool and rented a jackhammer every day. I worked general construction contracting a couple summers between college. the pool he got put in is a one week job and did not need a jackhammer except to ruin his peace and run up the bill. if they hit stone it's sandstone: they could have just pushed through it with the backhoe they rented to dig the hole with: i know because i collect rare rocks and i have some local sandstone, it's what's under the entire damn town: had to have some of the local rock in my collection: it came from the local superfund site, just on the edge where it wasn't contaminated: i got it from the site supervisor. anyways the contractors absolutely fucked my neighbor over. he both is and was an absolute idiot. he is a scientist and knows his science and nothing else.

i mean i'm an idiot. i know how do my music and nothing else. i get it.