Thanks will look at pg shots and see how i get onHi @matt2904 , adding a VG nic shot to a 70vg shortfill increases the overall VG content making it thicker so the coils you're using may struggle a little, especially at the wattage you're vaping at.
I balance my shortfills out with pg nic to bring the ratio to nearer 50/50. I also only vape at around 12-15 watts which will also help in increasing the lifetime of the coil.