DaveT - 2/13/2016 2:25 PM
MDW is pointing you in the correct direction. No one can tell you what amount of breathing gas you might need at99 feet without knowing how much gas you breathe. The class should educate you on gas management and calculating gas requirements. The Instructor should be able to then help you decide what redundant gas you should be using for specific dives. Along with the bottle, the method of carry comes into play.... once again ask your Instructor, that is what you are paying them for.