I may have asked this in another forum, but never to the vets. What exactly is a bottom feed mod? I understand it is a mod which has a bottle that supplys an atty from inside the mod, but how does it work? What kind of atty do you need to use? How does the liquid get to the atty exactly? I am asking this because I am thinking of either trying to get a Rio Grand or a VVPV from NotCigs. The VVPV has a drip on demand system, but the Reos are bottom feed, and I want to know more about the bottom feeders