So I upgraded and got the new Cool Fire IV TC 100w sub-ohm 3300mah. I'm currently using the BVC Clapton coil for the isub v tank I've been exsperimenting with it, and one coil only lasted me three days, when I've heard people say their coil lasts them two weeks. Is it the coil, is it junk, should I go with a nickel 200, or titanium, or the Stainless steel coil. What is the best coil that lasts the longest, For the isub v apex tank?