2 Tank Dive, Nitrox for Both?

[boulderjohn]

I haven't been to Cozumel in many years but in my experience, the operator you use makes a big difference. Some operators use high capacity steel tanks, and they aim for lots of bottom time. If you use one of those operators, I recommend nitrox on both dives. If you are diving the more common AL 80s and doing shorter dives based largely on the fastest breather in your group, one EANx tank will be plenty.

I did my first nitrox dives in Cozumel nearly 20 years ago, and it was different then. It was very common for dive shops to allow only one nitrox tank per trip, and you could only use it on the second dive. On one of my trips, I had requested my one nitrox tank (32%) and wanted to use it on the first dive (planned to 90 feet). The DM would not allow it, and he gave me a lecture in front of everyone about how dangerous it was to use nitrox on a dive planned for only 20 feet above the MOD--I might lose buoyancy control, accidently drop 20 feet, and go into immediate convulsions. He acted as if I were an imbecile for even considering it. On another trip, I was allowed to use nitrox on both dives because I was an instructor, and they decided I might have the skill to stay above that magical sharp MOD line that marks the difference between a safe dive and instant, agonizing death.

In later years, the operators I used were more enlightened.

 

[rjack321]

That's utterly insane and irresponsible.

It's mexican partial pressure blending...

Take responsibility for your gas. Analyze every tank for O2 and CO. Even the "air" tanks

 

[ChuckP]

It's mexican partial pressure blending...

Take responsibility for your gas. Analyze every tank for O2 and CO. Even the "air" tanks

Hunh?? I know one guy partial pressure blending - everything else is membrane. That one guy is a small shop.....

 

[rjack321]

Hunh?? I know one guy partial pressure blending - everything else is membrane. That one guy is a small shop.....

when you end up with 40% instead of 32% its almost always a PP error overfilling the empty or partial empty.

Its hard to screw up CB tanks that bad unless your one of those shops that double pumps every tank by filling with 40% then topping with air to make custom mixes (which is very uncommon in the Playa del Carmen area at least)

 

[Barnaby'sDad]

when you end up with 40% instead of 32% its almost always a PP error overfilling the empty or partial empty.

Its hard to screw up CB tanks that bad unless your one of those shops that double pumps every tank by filling with 40% then topping with air to make custom mixes (which is very uncommon in the Playa del Carmen area at least)

It was partial pressure blended. In the U.S. though...not Mexico.

 

[1967Goat]

Great advice everyone, thanks!!! I don't have my own tester, but I do remember how to test. Hopefully Dive Palancar lets us test the Nitrox using their meters.

Interesting thing about air consumption. I live in Conifer, Colorado at 7,400' elevation. I am a bit overweight at 230 lbs. (Hey, round is a shape ya know). With being a little fat and a bit of a rookie you'd think I'd be an air hog. Actually the opposite! When I dive I usually have the most air left in my tank, even more than the DM's! We chalk it up to the altitude where I live. Our small group has ended our dives and I've still had ~800+ PSI in my tank. I've asked the DMs what their air was, and its usually a little less than me. They are usually surprised.

@boulderjohn ..I've been meaning to PM you at some point. I'm less than an hour from you. I was going to try and take a class or at least touch base with you this past summer, but stupid Covid pretty much out the kabash on that. I'll be in touch with you at some point this winter or next Spring.

 

[boulderjohn]

ulderjohn ..I've been meaning to PM you at some point. I'm less than an hour from you. I was going to try and take a class or at least touch base with you this past summer, but stupid Covid pretty much out the kabash on that. I'll be in touch with you at some point this winter or next Spring.

I look forward to it.

 

[BRT]

Hunh?? I know one guy partial pressure blending - everything else is membrane. That one guy is a small shop.....

Is Meridiano on membranes now?

 

[ChuckP]

Is Meridiano on membranes now?

I was told they were and had no reason not to believe it. I'll ask tomorrow.

I stopped in today and I think they are partial pressure blending - that was a difficult conversation that quoted me tank prices three times before he said, si, partial pressure LOL

 

[BRT]

I was told they were and had no reason not to believe it. I'll ask tomorrow.

I stopped in today and I think they are partial pressure blending - that was a difficult conversation that quoted me tank prices three times before he said, si, partial pressure LOL

I heard a few years ago they were PP blending. They probably can buy O2 for next to nothing with their gas supply connections.