100ml Shortfill E-liquids are typically supplied in a 120ml bottle containing 100ml of nicotine free vape juice. This leaves you 20ml of space to add two, 10ml nicotine shots. Adding two nic shot will produce a 3mg mix.
Typically, 100ml shortfills are more expensive than a 50ml shortfill, however you’ll of course be getting double the amount of liquid in comparison. Working out the cost per ML of liquid, usually there is a considerable saving purchasing larger bottles of E-liquid when compared to smaller bottles.
Absolutely, it’s perfectly fine to vape 100ml Shortfills without adding any nicotine, this is also known as 0mg vaping. The flavour may be more intense due to the shortfill not being diluted with nicotine shots, however extra flavour can certainly be regarded as a positive, not a negative.