I don't own a Geni Tank but it looks similar to a Protank. The coil head probably has small holes for the wicking. It probably uses silica wick wich doesn't wick very well. It's really old tech.
I usually use 60/40 or 70/30 VG/PG. You might be able to go with 60/40 VG/PG but you'd have to keep your watts set pretty low.
16 mg sounds pretty good. I started on 18 mg with my CE4s and Protanks but I went up to 24 mg for a month or two because I was having strong cravings.