Nitrox 32 first dive, air second dive?

[keesmon]

Last year, diving on air in Cozumel for 6 days we came very close to deco obligations on our computers. Something we would like to avoid going forward. We dive AL80's generally.
We are diving in March for 7-8 days and will be doing the usual 2 dives per day, with a night dive mid week (followed by an off day).
It makes sense to me do dive Nitrox 32 on the first dive, as it is usually the deeper one of the two.
My question is regarding the second dive. We could dive Nitrox 36 (as the second dive is generally more shallow), or we could dive air, knowing that we have plenty of recovery time after the second dive.
We tend to do dives around 55-65 minutes following the usual Cozumel dive profiles. We are diving with 3P.
In your opinions, what does diving the second dive on Nitrox 36 buy me vs. diving the second dive on air?
I'm not opposed to shell out the extra $10 per tank, but I'd like to see what other veterans of Cozumel diving AL80's generally do on two tank days. In other words, is it worth it?
Thanks in advance.

 

[Goingforsound]

Given my experience in cozumel with depths you could be diving 36 on both dives on regular sites.

I never had to go below 90 feet, and usually my dives were above 80.

Maybe it was my Dive Op but I only saw 32%?

 

[Lorenzoid]

In your opinions, what does diving the second dive on Nitrox 36 buy me vs. diving the second dive on air?

Why not plug the numbers into your table or computer and see for yourself? I mean, using 36% on the second dive will give you more no-deco time than using air, as you're aware. Exactly how much extra no-deco time is a good question. Unless someone has firsthand experience from diving both air and 36% on their second dives, all you're going to get are people's guesses.

We use Aldora, and they typically do 32% on the first dive, 36% on the second, with the goal of everyone getting a good 60+ minutes on BOTH dives. It seems to work. I haven't tried air for the second dive, and haven't plugged it into the tables/computer, so I don't have any advice for you.

 

[tursiops]

Air is for car tires.

 

[redacted]

Air is for car tires.

And divers who would rather not waste $20 a day. Usually, all Coz dives are doable on air, but you do have to keep an eye on your N2 loading.

 

[Lorenzoid]

Air is for car tires.

But the $70 saved by using air, uh, I mean, EAN21, is a lot of margaritas.

 

[tursiops]

But the $70 saved by using air, uh, I mean, EAN21, is a lot of margaritas.

$70? Over how many days?

 

[Lorenzoid]

$70? Over how many days?

I just figured 7 days, using the OP's statement that 36% costs $10 more than air per tank.

 

[keesmon]

Thanks for the replies so far.
Correct. We're talking $70 over 7 days.
The question was:
Following typical Cozumel dive profiles and having done dive 1 on EAN32, will I get anywhere near NDL's on dive 2 diving EAN21?
When diving 2 consecutive tanks of EAN21 we got closer than I liked, so that's why I'm asking.
I'm assuming that the next morning we're all cleared and ready to start loading from scratch again.

 

[Goingforsound]

Depending on your dive op the other divers might be on air. If your are following the group you will be within the ndl. Nitrox would be added safety factor for yourself.

May vary depending on operator