I've been running my evod's with a total of 6mm silicon wicks. 3mm wick coil with 3mm top wick.
Works very well for me, no leaks when filled to the brim, little to no gurgle.
As for the protank, gave that up as a bad job, I can't get that to work very well. Moved on to the Anyvape Davide. Finding that a lot nicer to work with, (personal preference).