This is what I don't understand. I know they're terrestrial and I know that a tub is perfectly suitable for them. Though I didn't know the dimensions of an average tub, so that's one question.
But what I want to know now is why a generic 30 gal tank is generally seen as acceptable but a 20L, which has the same floorspace, is not. I've gathered from the above post that a 30L is better, but then why do most not complain about a 30?