I first tried with 3mm coils & to much cotton caused the wicks to twist when i put the chimney back on & caused leaks.2.0mm & 2.5mm coils easier to wick ,i cut the bottom of the wick into a shallow V shape.The pointy part goes just into the juice channel & the top of the V level with the deck.
Dual RBA deck is easier to wick.
The single deck is like my Lemo 2 , good if you get it right but takes a little getting used to.
When i rewick i bottom fill the tank so if i have not got it right i can reposition the wicks without having to empty tank.
Shutting the airflow off & leaving a small air bubble when filling the tank also helps to prevent leaks.
Thanks for the info