Better SAC rate switching from Poseidon Xstream to Apeks

[BrianGB]

Over the past year I have moved away from diving my Xstream regs and switched to the ATX 50's (diving sidemount). My last cave week in Mexico I noticed a considerable difference in SAC rate. With my Poseidon's', I was getting an average of 19-20psi/min. Switching to the Apeks, I was at an average of 15-16 psi/min.

I know the 2nd stage of the Xstream is upstream, and I'm contributing that as the main factor, a friend who dives Apeks talked about "sipping air" and I didn't know what he meant unit i switched. When you took a breath from the Xstream, there wasn't any "sipping" feeling. During my cave course, my instructor used a bubble gun, vs pushing my purge button, simply because if I try and block the flow with my tongue, I felt my tonsils would be ripped out.

Just wondering if anyone else noticed a difference?

 

[tbone1004]

Over the past year I have moved away from diving my Xstream regs and switched to the ATX 50's (diving sidemount). My last cave week in Mexico I noticed a considerable difference in SAC rate. With my Poseidon's', I was getting an average of 19-20psi/min. Switching to the Apeks, I was at an average of 15-16 psi/min.

I know the 2nd stage of the Xstream is upstream, and I'm contributing that as the main factor, a friend who dives Apeks talked about "sipping air" and I didn't know what he meant unit i switched. When you took a breath from the Xstream, there wasn't any "sipping" feeling. During my cave course, my instructor used a bubble gun, vs pushing my purge button, simply because if I try and block the flow with my tongue, I felt my tonsils would be ripped out.

Just wondering if anyone else noticed a difference?

my experience is the opposite with a better SAC rate on my Jetstream/Xstream vs Apeks/Deep6. The total WoB of an Xstream on inhale is lower than it is on an Apeks so any SAC rate change would have been based on your breathing pattern not the regulator itself. They do have a violent purge though!

 

[BrianGB]

my experience is the opposite with a better SAC rate on my Jetstream/Xstream vs Apeks/Deep6. The total WoB of an Xstream on inhale is lower than it is on an Apeks so any SAC rate change would have been based on your breathing pattern not the regulator itself. They do have a violent purge though!

That is interesting to read! I would have thought my rate would've been better as well.

Thanks for responding!

 

[scubadada]

Probably my mistake, I thought the majority of the WOB was on the exhale

 

[Jack Hammer]

My personal experience is a properly tuned regulator will have less WOB than a regulator with a less than stellar tune.

 

[tbone1004]

Probably my mistake, I thought the majority of the WOB was on the exhale

Below is the breathing curve for the X-Stream and it certainly follows that. Apeks is a bit more balanced IIRC but you don't really perceive the exhale WoB the same way and it is well within the levels of top performing regulators. Any difference in SAC that I have been able to sort out is based mostly on the way the regulator breathes vs. the way your body breathes. I'm a musician so my body is used to very rapid inhales and the Poseidon almost requires that type of breathing, same with a double hose. "Sipping" on the regulator is something you can do with a properly tuned Poseidon but it will certainly try to open all the way as the venturi is quite strong.

 

[grantctobin]

Over the past year I have moved away from diving my Xstream regs and switched to the ATX 50's (diving sidemount). My last cave week in Mexico I noticed a considerable difference in SAC rate. With my Poseidon's', I was getting an average of 19-20psi/min. Switching to the Apeks, I was at an average of 15-16 psi/min.

I know the 2nd stage of the Xstream is upstream, and I'm contributing that as the main factor, a friend who dives Apeks talked about "sipping air" and I didn't know what he meant unit i switched. When you took a breath from the Xstream, there wasn't any "sipping" feeling. During my cave course, my instructor used a bubble gun, vs pushing my purge button, simply because if I try and block the flow with my tongue, I felt my tonsils would be ripped out.

Just wondering if anyone else noticed a difference?

Was this difference during a single dive? E.g Apeks on left, Poseidon on right? Were both at the same depth?

I’m guessing different factor at play. Wetsuit vs drysuit, different avg depth, flow vs no flow, etc.

 

[BrianGB]

Was this difference during a single dive? E.g Apeks on left, Poseidon on right? Were both at the same depth?

I’m guessing different factor at play. Wetsuit vs drysuit, different avg depth, flow vs no flow, etc.

Great question!

Where I realized the difference was during a week of cave dives in Mexico. That is where I really pay attention to my sac rate, and compare them with the others in my team.

The time between trips was 3 months apart, and have gone a couple times since then and have noticed similar sac rates. The rest of the gear was the same. I did switch from a Katana wing to an Xdeep in my recent trip in the fall but that didn't affect anything

 

[Underwater Tourist]

Are you sure both regs very tuned the same/similarly?

I was training in mexico and my instructor had a very similar sac rate so after each dive we would come out with a very similar amount of gas left (adjusting for drills, exercises etc).

But for one dive I opened up my apekses (meaning increased how much gas they supply) and after the dive was over my instructor asked if i got bored and that's why i turned the dive? (when we came out he still had plenty of gas left, but i reached my thirds during the dive).

What ended up happening is because I opened up my regs and was breathing in more gas, my buoyancy breathing rhythm that i was used to got screwed up. So not only I was breathing in more gas, but I also had to breathe more often to keep the buoyancy where I wanted it to be, which led to a much higher sac rate. I actually have a video from that dive somewhere, and you can really see that my exhales produce an absurd amount of bubbles.




So maybe something similar happened to you? Poseidons delivering too much gas

 

[scubadada]

Below is the breathing curve for the X-Stream and it certainly follows that. Apeks is a bit more balanced IIRC but you don't really perceive the exhale WoB the same way and it is well within the levels of top performing regulators. Any difference in SAC that I have been able to sort out is based mostly on the way the regulator breathes vs. the way your body breathes. I'm a musician so my body is used to very rapid inhales and the Poseidon almost requires that type of breathing, same with a double hose. "Sipping" on the regulator is something you can do with a properly tuned Poseidon but it will certainly try to open all the way as the venturi is quite strong.

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On only a very small number of dives with a very high effort and breathing rate have I thought I have been aware of the WOB associated with exhalation. I stopped my activity and took a little time to recover before continuing. I have never really been aware of the WOB for inhalation. This observation is not very scientific, it was only that I was aware of more work on exhalation.

I am more used to seeing regulator testing as a flow loop of inhalation and exhalation, that is an easy way to see the different work associated with various segments of the breathing cycle