My setup mirrors yours. I have been using 70pg/30vg and 50vg/50pg.
I switched from KGD cotton to the latest version of Cotton Bacon. I have never used celu cotton.
Hope this helps if you are a cotton user:
1. Fill the GEM's coil with the normal amount of cotton that works with the attys you are used too.
2. Make sure the cotton is not twisted in the coil. Fill the GEM deck's outher channels with the excess cotton, make sure it fills both outer channels. Cut your the excess/wick (close to) flush with the building deck.
This is what I use to cut the cotton:
KNIPEX 78 61 125 Electronics Super Knips Comfort Grip - Wire Cutters - Amazon.com
I am pretty sure there are cheaper equally efficient cutters.
You have to leave plenty of room for the cotton to absorb and expand in order for it's capillary action to be efficient. The "shallow U" part of the deck that is next to the air channel and coil, can have an equal amount of cotton as the coil, think of this "shallow U" as being part of a juice dam. The outer deck channels should be filled with cotton but not as tight as the coil or the "shallow U" Think of this as a wicking/feed control.
3. After filling and cutting the cotton flush with the outer deck channel, take a small pointy object like a needle, (I use a small gauge hypodermic needle that I cut the sharp point off) and take the cotton out of the outer deck channel and fluff it lightly without distorting the natural strands. You will notice if you left the cotton twisted and or uneven, now is the time to correct and or re-place the wick. Take your pointy object and place the strands in a natural fashion, meaning the strands that naturally fall/lay on the bottom take precedence over the ones on top. Lightly fill the outer deck channel with enough cotton keeping in mind your e-liquid's viscosity (remember cotton expands).
Here is where I would have to say the thicker the liquid the less cotton in the outer channel depending on your wicking media.
You should have some extra cotton sticking out of both the top of the deck and the side of the outer deck channel, cut it off, and redo this step until you feel that your cotton will not become too dense with e-liquid, causing it too stick together diminishing the cotton's capillary action at the same time gauging that you have enough to prevent a leak. I cut my cotton a touch lower than the screws and keep it flush with the deck's wicking channels.
If you over wick the outer deck channels, you will not have enough room for air/vacuum to properly compensate.
I do not vape high VG, but this is my way of wicking the GEM and it does not take me long, no dry hits. Just a suggestion, hope it helps.
