reaction chamber of a skimmer ?

[Dom]

why the column of a skimmer is always round ? i know that whit somme kind like a aerofoamer it need to be like this cause the flow spin inside, but whit other like a aqua-c or PM bullet ? if the column was square does it make any difference ?

the goal of my question is , im looking to make my selves a new DIY skimmer for my new 265 gallon systeme , and i was thinking why making it round if square can do the samme thing

beside that making it square can cost less , the price of acrylic tubing is kind of expensive