Ok guys I have had a Cigar Oasis XL for about 4 months now and it was used when i got it. It has never shown that it was running low on water, but I have added distilled water once or twice, just to be sure. Is this recomended? I know they sell replacement cartridges, but are they nessesary everytime one runs dry or can they be refilled? Do I use plain distilled or a solutionof some sort?