I put that Zephyrus sub-tank aside because it was leaking right from the get go with two different pre-built coils and figured I just got a bad tank. Looking at it today it dawned on me, maybe I needed to fill it rather then just enough juice to cover the juice intake ports in the bottom of the coil, sure enough that was the problem. So I vaped on it today using one of the pre-built nickle coils, it was OK. Tonight I decided to try a built on the little RBA deck that came with it, gave my first try using dual coil kanthal and my old standby rayon for a wick. Hit at .21 ohms and it hits like a champ, the flavor of my favorite juice, well I realize I've never truly tasted it until tonight, wow! Yeah I have really been missing out vaping on my little old pro tanks! I love this tank, and my juice tastes oh so good! Can't wait to build it up with nickle!