A "doubler" will have your 30ml bottle filled only half method, permitting you to fill the remainder with the pure nicotine mix of your picking. If you are topping up, after that you would normally be utilizing a PG base with a high degree of nicotine such as 100mg/ml. On a global range, this base is additionally not so typical.
http://cashwivc351.iamarrows.com/thin-down-vape-juice-with-water