Spare Air questions

[Vtach]

Spare Air system is generally useless for most diving applications. Your best bet is to add some sort of redundancy to your air supply through either an extra tank (pony, stage bottle or doubles) and an extra first and second stage regulator. The next best option is to use a dual outlet valve on a single cylinder with 2 first and 2 second stages.

I prefer using double tanks with a dual outlet isolating manifold and stage bottles when necessary. They are definitely more costly but the redundancy is hard to beat.