I use these Smoktek Single Coil tank replacement cartos:
Single Coil XL Tank Cartomizer for the SmokTank XL
I had been using the dual coil variety of these only because that is what originally came in my tanks. But I sometimes would get a harsh, burnt taste with them, even tho I was quite sure the carto was getting enough juice. After doing some investigation here on the forums, I decided to give the single coil variety a try.
The single coils give the same flavor and vapor production as the two coil. No more burnt taste or harshness. I'm getting longer battery life with the single coils.
I use 2.0 ohm resistance for my 3.7v mods. 3.0 ohm for the Provari. I get some with one hole lazer drilled and some with two holes. The single holes get the 50pg/50vg juices, the two holes get any juice with 60% or more vg. I get excellent juice flow with these as long as I choose the correct number of holes to the viscosity of the juices.
I stopped self-punching my cartos as I was warping too many of them with my punch tool. Being out-of-round, they often were difficult to get through the endcaps. Buying pre-punched cartos provides me with consistancy. It's worth it to me.
I fill my cartos by dripping into the top, using a wooden tooth pic in the airhole to keep unwanted juice out. I patiently fill until the polyfill looks like a slushy drink. Remove the tooth pic.
I use the Big Daddy Vapors Slap-Yo-Momma tank tool next. It simplifies and speeds the tank assembly and juice filling by leaps and bounds. (It also protects the tank's o-rings, which keep the tank from leaking.)
It goes into the top of the prepped cartomizer like a drip tip, then I put it and the carto into the bottom of the assembled tank. The carto goes in only 3/4 of the way, and I fill the tank with juice through the opening of the top endcap. Once filled, the carto is pushed the rest of the way up. SYM tool is removed and replaced with a drip tip. Ready to vape. See video below.