I slot my cartos vertical, the length of the tank interior. I have found this gives the most consistent and quickest carto saturation. I use the boge xl standard cartos on a provari at 5v with a cheap 5mil tank. No dry hits, no topping carto off. Lasts all day with no fiddling at all. Using diy super conc. flavor honey flu cured with 80% pg/ 20%vg. Cartos lasting a week with this setup, get 2 weeks from a kanger but dont like the draw- like a milkshake through a straw. Hope this is useful to someone.