Wow I never knew that.. I've been filling both of mine up all the way.. I couldn't figure why this liquid floods but a 50/50 mix doesn't in the other tank. But I turned my voltage up from 3.7 to 4.8 (all the way up) and also added another flavor wick made from cotton above the other two that came in it. I was examining my coils (I have two replacements) and saw that the hole under my rubber seal where the wicks stick out had a tiny gap. Two flavor wicks and the vape wick weren't filling the gap completely and the e juice was getting in there. It seems to be vaping ok now. So I guess the problem was with the coil and wicks not the juice.
Yes, 90% of the time when I've seen a "leaking tank" with pre-built coils it's generally the coil... If you build a coil for yourself you take your time and get it right... If it doesn't come out quite right, you throw it away and start again... Now imagine the guy sitting there building these things for 12 hours a day... He's going to be whipping them together as fast as he can to meet his quota... If one isn't quite right? Oh well, throw it in the bucket and start the next one... who cares...
As for the other post... I'll be honest with you... I'm not exactly sure where that came from, though I've seen it stated several times... It is NOT my experience though...
On many tanks that are bottom coil, they work on a negative pressure system. Meaning the chamber outside the coil is in a vacuum (due to the pressure of the liquid pulling down). Because of this you must maintain a pocket of air... Because air can expand... Liquid can't... So I never fill my bottom coil atty's completely full... I leave probably at least 15% of the top of the tank empty... That's not much, but it's plenty to serve it's purpose...
On the other hand, with everything from my kanger tanks to my kayfuns, I'll run them down to the last drop before refilling... In fact, in my kayfuns I usually run full SS mode, meaning you have no window to see liquid level... The only way you know it's "time to fill up" is when the vape starts to get dry... I've NEVER had leaking/flooding issues with any of my tanks due to the juice level getting low... Going from extreme hot to cold or vice versa? Yes... Which is to be expected regardless of the juice level... Bad coil? Yes... Messed up o-ring? Yes.... But never because the juice level was too low...
Like I said, your results may vary, but I just know for me personally I've never had this happen... Anyway, glad to see you got it resolved!!!!