nic bump

I am about to buy what was left of Reality from OM Vapors. They only have 3mg/WTA left in a 120ml. How much nic should I add to bring it up to 15mg? 12 or 18 is good if it's simpler. Thank you in advance. :anyone:

I took a 30ml 100%vg bottle out of the freezer a few weeks ago to add a kick to a pre-made eliquid. It didn't do anything. I just took out a 60ml bottle. Do I need to let it breathe first or just add a few drops. I'm at 18ml but need a 24mg for the occasional bump. I could do just...