i keep seeing the ego tank atomizers but cant find a thorough explanation as to what they do. it appears that you use a cartridge with them. but do you have to use the cartridge? can you just drip into it and use a 510 driptip?? im trying to figure out what makes it tank-like, is it just the cartridge holding a reservoir of juice, or does the atomizer itself hold more liquid than a standard atty?