[upsidesinclude]

If you wanted to be pedantic you would correct the statement because there is no glass.

To be excruciatingly specific.

[abduhl]

The article refers to the aquarium as glass throughout it.

[kayodelycaon]

The material used is plexiglass, aka acrylic, a type of clear plastic. Actual glass is probably too brittle or expensive.

People use "glass" to mean the clear part of a window, not the actual material, in this context.

[upsidesinclude]

Plexiglas®

A trade name.

[abduhl]

I'm glad to hear that you'd agree with me then that a correction saying "there is no glass" would be inappropriate because when someone says glass they mean the clear part of the tank.

[seattle_spring]

This may or may not be your intention, but fyi you are coming off as extremely condescending bordering on /r/iamverysmart level tones.

I'm no expert, but I know that a hot tub on slightly uneven ground has a good possibility of bursting and ruining the tub due to how much stress the water will unevenly put against a side. I don't see why the same underlying reasons wouldn't apply here too.