I don't have experience with your particular tank, but I've dealt with my fair share of spitting on others. Based on the info you gave, I'm definitely thinking you've got something mechanical going on.
If you have something to remove your juice without wasting it, drain that sucker and give the tank a good breakdown - including the coil head. Reassemble making sure your o-rings (if it uses them) aren't getting pulled from their slots. A bit beyond finger tight is good enough.
As for the coil, from what I can tell from pictures the Atlantis' head is basically a cartomizer, and should be easy to break down and reassemble. Pay close attention to what the chimney looks like (tons of moisture?) and check your wick. It should be obvious if you're flooding, it could be a crappy wick (hope it came with cotton! Rewicking time) or it could be as simple as poor factory assembly.
It's good to get to know your topper early on in any event, and if you're vaping out of the box, disassembly and a wash isn't a bad idea in the first place.
I'll ad a vid here if I can hunt one down.
[EDIT] Jeez, ceramic wick and everything? I'll leave it to you to decide if this is worth the effort, but if nothing else, the vid is incredibly detailed. I will still recommend breaking down and reassembling the tank even if you leave the atomizer head as is. Never seen this guy before but man, is it nice to not have to hit mute.