Fabricating steel stand - which steel do I buy?

[Myka]

Ok, so steel is definitely not my forte. I used to be a carpenter by trade, now I'm a true reef junkie. Anyway, it suddenly dawned on me that hubby has a welder and knows how to weld. I'm pretty sure 1" square steel tube is plenty for my 36" long 69-gallon tank, but before I go buy the wrong thing, is there a wall thickness or a gauge or a particular name-type I'm looking for? Or is it just a standard thing?

I sent Grizz a PM yesterday. He hasn't replied yet, and I'd like to go get this stuff today.