Hi - I am enjoying my Spade (the purple one!), and I ordered a 510........Still doing the learning curve thing........I was wondering, are there larger carts that hold more liquid that would fit these? Seems like I am always refilling However, I will report that I have cut down on the analogs, and that my sense of smell is ever so slightly better (I am actually beginning to smell cigarettes - yuk)!). Any advice or comments are appreciated!