Fill Hole Leaking

[Sinister Dexter]

I've seen recommendations to leave the fill hole open to improve wicking. When I try this on my DUD, it leaks juice whenever it's tilted. Now I see some new rebuildable tanks don't even have screws for the fill hole, like the Bliss and the Z-Atty Pro. Are these intended for upright use only? Or is there some trick to stop them from leaking?

I'd like a better genesis-style device but I'd like something I can carry around in my pocket. The Penelope looks nice for that but they are hard to find.

 

[nnote]

You could put a small roll of SS wick in it

 

[MrKV]

My Cobra has a fill screw but I leave it out to help with wicking. I can hold it upside down forever and the only liquid that is going to come out from the tank is what's dripping off the wick.