yea, there's so many variables with vaping. When one component works, another one doesn't. Once you think you (me) have everything figured out, something happens that has no explanation. I had lots of flooding issues back when I first started using tanks, I started with the chibi and the mini sub. After awhile, air would come in through the vinyl grommets. All carto tanks work basically off vacum and when the seal around the carto gets weak, air can be sucked in as they are vaped.
I've had no instances of flooding once I started using the dctanks. My issues now are my juice starts tasting "off" after a couple days in the tank. I'm thinking it's just ME. taste is so subjective and some people can taste things that others can't. I've read post after post where people lose their taste for a favorite juice. It happened to me one time, right in the middle of a bottle. BAM.. all of a sudden, my beloved waffle, that I had happily vaped for months, tasted awful!
I've heard people talk about a tank flooding because of air pressure, like when driving up and down a mountain. I've driven up and down Black Mountain (NC) several times and never had an issue with my tanks flooding.