This again? I was under the impression this “method” was already debunked by half the board the last time you brought it up?Those who carry a back mounted pony bottle as I do might want to consider doing what I do.
Since I "use" my pony bottle on virtually every dive- I consider it a redundant emergency source of gas during the dive (bailout) and then use it as a "stage" bottle towards the end of the dive- meaning that I allow my main tank reserve to drop below 500 psi even at depth since I have the pony bottle- it allows me to extend almost every dive.
Since I treat the pony bottle as such, I have a transmitter on the main AND the pony tank and my pony bottle wrist computer is on my left wrist. It's not only streamlined and functional but it looks cool and when people say "why do you wear a computer on each wrist?" it always makes for great conversation/debate as to how I utilize my pony bottle to extend my dives.
The pony bottle computer also serves as a backup (I set it to the same Nitrox blend as my main tank so it accurately tracks my NDLs).
To OP, please don’t do this.