I use Foggers at work. 4.5ml. That may be too small for you, but the V6 is top fill and easy to do. I wear it on top of an 18350 mod, so I run thru 2 batts per tank. A full tank and 2 batts usually lasts me all day, but I carry a U-can and an extra spare batt just in case. My full size Nauti is like 6ml, probably the biggest tank I have. You might look at that. I don't use it much because it has pre-made coils and I sub ohm on a mech. Just got in a regulated box, though, so that may change. It's pricy, but you might want to look at a bottom feed RDA and a squonk-box. There's a dude in the suppliers forum who makes one with a 6ml bottle.