You must be talking about subroasa .... well he is correct in a way and incorrect in others.
Note how many times he says "if". Although this should be moved to another thread, it is not really the bioload of the puffer itself that requires a min of 5 gals, it is also the swimming space (mine hunts in all 30 gals he has), and the destruction they leave behind. The partial bodies can foul the water very quickly. Eliminate the "ifs" and you eliminate the variables. "Will" becomes the optimum solution. Anything can happen on an "if". Think along these lines: "If I do this", what is the next logical statement? Would it be "This will happen..." or "This should happen.."? Since the person is talking in abstracts the latter is logical. The person can't know what "will" happen "if" it hasn't. Am I confusing you yet?
The statement should have read "3 gal tank will work, when you provide x% of plant coverage, x amount of filtration, x% of weekly water changes and x% of food". The poster dealing abstracts can't provide that information. Here these guys and gals KNOW what WILL work. There are no abstracts, but there is a little wiggle room for experimentation.
if you follow me, you avoid stepping in the crap that I just did...