>>2570683Please list your gear,
I would highly recommend taking a SSI basic open water scuba course. Most of it is online self-paced learning and its not super expensive. It will get you the fundamentals of diving, understanding depth and
To answer your question about gas mixtures and diving, basic open circuit scuba w divers just use regular old compressed air that's at a diver standard. some people and mostly commercial divers use surface supplied air from a compressor topside but there are some recreational "hooka" systems out there.
There's Nitrox (not to be confused with Nitrous oxide), also called enriched air which is just a trade name, which all it is, is air that has a higher % of oxygen than regular air (which is 21% o2) commonly at 32% O2 but you can set it to as high as you want with the recreational limit at 44% O2. Anything higher is considered technical. The reason you would use higher o2 is that it increases your no decompression "bottom time" and reduces your deco time (if you have to decompress), but it also reduces your max operating depth. The higher the O2 the shallower your max depth is with %100 O2 being something like 20ft. Violating this can cause you to have convulsions and death vai drowning because o2 becomes toxic at depth. The term used for this is partial pressure of oxygen which for the human body the PO2 is 1.6 and is physiological hard limitation. At aprox. 250ft even air (21% O2) becomes toxic so you have to use hypoxic mixes and that's where trimix comes into play
Trimix is basically any mixture of Helium with any other gas something for great depths a hypoxic level of o2. Reason you would use Trimix is because it reduces nitrogen narcosis (basically getting high at depth) since you are replacing nitrogen with helium. These days its rarely used outside of re-breathers (which recycle gases) because Helium is now super expensive.
There's a lot to known, recommend reading the US navy dive manual too.
