I vape 70/30 pg/vg stuff at 18mg. I'm going to buy about 500ml nic base in 60mg, I have the option to get the nic base in 70/30. Now is this the most efficient mix of nic to buy? I'm thinking if I get the right formula of nic base I could skip buying vg at all and just mix pg and my nic base to get my 18mg with 30% vg. Is this possible?