resistance plus 2. 3ohm carto plus 2 = 5 volts = good starting point at around 8.5 watts. i would say adjust to taste, start low and work your way up. try out different voltages, you may find you like one
juice at a lower voltage than another. once i got into higher voltage i grabbed 3ohm attys and ran my lavatube all the way up to 6.0v with everything. it wasnt till i popped my last 3 ohm that i figured out one of my favorite juices blossoms at 8W. i think i was killing off one of the flavors at 11W