Not exactly sure where to put this, but I think this is right. So I have been building for about the last year. I can build coils fine, usually contact coils but lately I have been spacing them out. Right now, I have a dual coil using 30 gage, spaced out coils in a Fogger V.1, on a provari. I have been vaping at about 4.0, give or take a couple .1's. The deal is, after about a half to two thirds of a tank, the taste starts to get off. I finish the tank off because I'm lazy and don't want to drain the Fogger. When I change the coil, its all black and gunked up. I can't understand why it is doing this. Is my wicking bad? Am I over stuffing the liquid channels with cotton? I have been using Japanese cotton pretty strictly. I didn't boil it. I didn't think you have to boil it. Anyways, any help would be greatly appreciated! Thank you!~