And, yes, you do have to do a lot of 'topping off' when it comes to cartos... that's just how it is with them. You might want to try the eGo Mega Dual Coil Cartos as well... that is if you have a eGo or the correct eGo/510 adapter. Or, you could skip all that and try out one of the 500 different 'carto tanks' that is out there.