I have 2 tens and a five. I may get a 20, but like Jim says - one leak would make me reconsider the choice. One of my tens needs a hydro test next time it is empty, so I hope it passes. I think the aluminum is prone to oxidation, if that is what they call it. I just know that at the last test I had done, I had to buy another tank because the first one failed due to the interior condition.