I have Bobas running thru a Et clearo with 3 refills and no head clogging so I don't know what the problem is with your mix. The KPB and Country combined should not be that thick as to gunk up a coil, but maybe with the biscotti (I have found bakery vapes to be rather dark and thick) is the real culprit. I have been running VR KY4 in one of the Mini Nova's and have found the vape to be almost harsh, I switched the clearo from a X2 manual to an X2 auto and the vape was MUCH less harsh. I dunno....maybe too much voltage off the manual for that liquid (which tastes amazing in a mini clearo or an esmart mini clearo).