Outside of the fluid dynamics people have mentioned here which ALL bottom feeder clearos have to deal with and expansion / contraction that can happen when moving from a cold house to a hot car which can cause clearos to flood....
A big part of the problem (most of...99% of the problem) with protanks v1 and v2, IS the 510 base which causes a restriction of the air that travels through the 510 and down thru the coil hole past the insulator grommet before it finally travels up thru the center pin to get to the coil and out to your mouth.
Heres a helpful diagram so you can see what I mean...
http://www.e-cigarette-forum.com/fo...anger-protank-airflow-fix-protank-airflow.png
from this thread about the 510 air restriction issue...
http://www.e-cigarette-forum.com/forum/clearomizers/482938-kanger-protank-airflow-fix.html
When the 510 base is screwed onto your mod, it slightly squashes the insulator grommet making it fatter in the coil hole which makes the air path even more restricted. This problem became even worse when kanger started using silicone rubber instead of the old harder rubber for those insulators. The silicone was much softer and would squash outward to the point of restricting the air path so badly in some cases it would be way too tight or even completely shut off. Most folks would compensate by not fully tightening their protanks to their mods. Kanger tried to address the blocked flow problem on protank3's with the dual coils by notching the sides of the center pins, but that led to them developing the air control base to get rid of the flawed design of the older 510 base piece. Probably the greatest thing kanger has ever done to improve their performance, imho.
Anyway, that restricted air path causes the user to vacuum too much e-liquid into the wicks and flooding the coil...or gurgling horribly.
Mini pro tanks use the ego connection and there is no air restriction before the air finds its way up the center pin. This is why mini pros and all the other kanger ego connected clearos dont gurgle or flood anywhere near as often as the bigger brother protanks and other 510 connected clearos made before kanger started making them with the air flow control base piece.
When you throw away that damned old 510 base and replace it with an aerotank base, you basically CURE 99% of what causes flooding and gurgling on the good old protanks v1, v2 and v3. The aerotank base holds your coil head in such a way that there is no restricted air path before the air goes up the center pin, much like the way air gets to the center pin on ego connected kangers. Plus you gain the advantage of being able to adjust the airflow "draw" to suit your personal preference. Tighter draw helps increase juice feed and slightly warms up the vape where looser draw gives more air and a cooler vape.
If you have a protank2 and a minipro laying around, you CAN put that base on a protank and you'll see the big difference in draw and less flooding gurgling getting rid of the 510 restriction really makes. But the aerotank base IS THE CURE.
sheeesh, didnt mean to write a book.
hth,
jon