structure for DIY float tank

I have built float tanks before with wood and fibreglass.

Now I'm living in another country and want to have a tank again, the option I want to build is like the zen float tank.

So I want to know if is possible to build the structure with galvanized tubes?

(I think the float tent has stainless steel)

will this kind of joints will hold?

how are they securing the structure? this needs to be super strong as it will be holding more than a ton of water...

Here link showing float tank design, footprint, etc...

page with info

Tank footprint

Now my question is, can I use just galvanized tubing? do I need to solder some parts? (hopefully easy to disassemble as I'm renting).