Dive which tank first??????

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SeaCayZee

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• Nov 19, 2009

• #1

Doing a two tank dive within rec. limits......
Have two tanks,
One is air, the other is Nitrox32.

Which tank should I dive with first?

 

mustang_5l

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I'm a Fish!

• Nov 19, 2009

• #2

Dive the higher % first.

 

fppf

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• Nov 19, 2009

• #3

depends on the dives, the depths, planned bottom times.....

But all things equal, I would dive the lower mix first, your chances of DCS are higher on the second dive. You will have higher residual nitrogen on the second dive, so use the higher mix then.

 

I

idocsteve

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• Nov 19, 2009

• #4

Generally speaking the deeper dive is first, therefore you'll get more bang for the buck if you use the Nitrox mix on your first dive, you'll get a proportionately longer bottom time from the richer mix. Also you'll enjoy a shorter surface interval and possibly have a higher energy level following the first dive which would be a better way to start the second, although the theory about this particular advantage of Nitrox is not proven.

 

zaberman1

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• Nov 19, 2009

• #5

The highest Acceptable mix for that particular dive

 

ptyx

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• Nov 19, 2009

• #6

Running following scenario with a Buhlmann deco model:

First dive: 100ft, 20 minutes bottom time
30' minutes surface interval
Second dive: 100 ft, 20 minutes bottom time

This is pushing it (to say the least) for recreational diving.

With air, then nitrox 32, I get 26 minutes and 25 minutes runtimes.
With nitrox 32, then air, I get 25 minutes and 29 minutes runtimes.

As you accumulate more deco, it starts to make more difference: if both dives have a bottom time of 25 minutes, air first gives you 36+34 runtime, nitrox first 30+46.

So my conclusion would be: for similar dives, nitrox last, but for recreational diving the difference is negligible.

 

Thalassamania

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• Nov 19, 2009

• #7

I'd dive the deepest END first, so it's likely Air first then Nitrox.

 

katdiver

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• Nov 19, 2009

• #8

idocsteve:

Generally speaking the deeper dive is first, therefore you'll get more bang for the buck if you use the Nitrox mix on your first dive, you'll get a proportionately longer bottom time from the richer mix. Also you'll enjoy a shorter surface interval and possibly have a higher energy level following the first dive which would be a better way to start the second, although the theory about this particular advantage of Nitrox is not proven.

Click to expand...

This is how I use my Nitrox. Deepest dive first with the optimum mix, longer bottom time, clear head when I surface. I always feel better after a Nitrox dive.