I am not Newton but this is my educated opinion, BJ's law
I have found when the tank is underneath and juice has to rise the best is 400 mesh, PG or VG, the juice has to rise by capillary action and the smaller the air spaces in the mesh the better it wicks, I only use 100% VG and have no problem with 400 mesh and hardly no wicking with 325 when the fluid has to rise, Most of the successful use of 325 over 400 is in attys with the tank above and fed by gravity and on these the larger spaces let it flow more juice down. This is not capillary action (wicking), it is flow by gravity. Wicking (capillary action) is a liquid rising against gravity.
It is a very easy lab experiment. Roll 3 in long wicks from different mesh #, put them in a small jar with 2 inches of vg and leave them over night. The next day you can see that the only one the juice has risen is the 400. 500 is even better if you can find it. Basic law of capillary action is, the smaller the hole, the higher the liquid rises. Doesn't matter if it is PG or VG.
After testing many wick sizes in my line type attys, IMO the more mesh you can roll as tight as you can of SS 400 mesh the better.
I started out with loose 25mm of mesh for a 2.5mm dia wick, then went to 35mm, then 45mm and now use 60mm very tight roll with a very small center hole for a 2.5mm dia. Seems that wicks are like the golf swing, every thing is opposite to what you would think.
Now if you want liquid to flow down, the bigger the holes in the mesh (325, 200) the bigger the flow (not capillary action) and the harder to control. Hard to put a valve on gravity and gravity causes different flow depending on the height of the liquid (another law of physics/hydraulics). So your flow is greater when the overhead tank is full and diminishes as it empties.