best Setup Pulsoximeter?

Your options are all day, during sleep or manually by opening the widget.

Unless you have a need for the information, leave it off. 

Doesn’t it enhance the body battery figures? Or used by anything else? Just considering whether it’s worth it but I don’t really see much of a drop in battery, maybe 2% overnight. 

Pulse Ox seems only to be used for altitude acclimation; it doesn’t appear to feed through to any other health or performance metrics (yet); there’s certainly no Garmin or Firstbeat technical info out there suggests it does and my observations after a few months with the MARQ supports this.

I have come to the same conclusion as Philip, that if you don’t need the altitude acclimation info, then turn Pulse Ox off as the battery hit is not worth it just to get an interesting number to talk about down the pub. If you are training at altitude, then I can absolutely see it’s value; just be prepared to charge the watch more frequently though.

Do we know for sure that it is actually used for altitude acclimation? I have my suspicion that metric is just based on time at a given altitude and i'm not sure much else plays into it. 

That’s the way I read DCR’s explanation of it (Firstbeat’s is very vague). 

The other confusing part of this is that in the GCM app, pulse ox readings are listed as being ‘Pulse ox acclimation’

In order to make any use of that metric you first need to undertand what it is about:

There are three possible options when you might be interested in that metric:

You are either hiking in the mountains or on a high altitude training or even trying to climb the Mount Everest, then it would be critical to know your blood oxygen saturation.

You know or suspect to suffer from sleep apnea, then this metric could give you a hint if you should go and visit a doctor to get a more precise analysis.

You suffer from some sort of illness like anemia and have a strong interest in knowing your medical condition.

In all other cases this metric is useless for you as a healthy person would always have a blood oxygen level above 97% which especially is independent of training, fatigue or fitness.

i agree with all your answers, i disabled Pulsoxy during the day and it is only activated during night when sleeping, but why it don't eat so much battery during night?

during night i loss 3% battery, when it runs 24h hours a day arround 25%?

the new breathing datafield during activities using this sensor too?

HermanB hopefully you have some answers?

sorry for kidding, but before you reach the top of Mount Everest the battery is empty 

anyway, it looks like the pulsoxy during night starts only after midnight till arround 4.00 am, same situation on your side?