Nitrox for 20 dives in 5 days?

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.. my favorite LDS recently. They charge $5 for air, $10 for 32%, a flat $15 for O2 <= 40 cu ft, which I find very reasonable. He was saying that the up-charge for nitrox is basically a labor charge. They go out of their way to fill slowly, cool the tank, fill some more, cool the tank, top off, etc. So I end up with a full 3442 psi of 32% in my HP tanks when cold, a proper fill. I respect that, they're my favorite for a reason.

...There is another LDS ...They have a water-cooled filling/blending station, and filled my tank in about 15 minutes with 32%. I was happy enough, but by the time the tank cooled down it was down to 3200 psi in my shed....

I see a lot of variation in filling practices too. My closest LDS has a very cold water tank. They give 5 minute fills & my pressure usually increases a couple hundred pounds after I leave. My second closest shop fills in open air & takes closer to half an hour. I usually don't loose more than 50-75 psi after the fact. Prices are close to the same between the two shops.

Most shops around here bank at least two nitrox mixes as well as air. At least one local shop has a couple flavors of trimix on tap as well.

Prices around here vary with the quantity of fills you prepay in advance. For air, you might get $7 for one, $60 for 10, $125 for 25, & $450 for 100. Nitrox is probably 3-4 bucks more per fill. Those aren't actual current prices, but they are pretty close.

I have another shop about 45 minutes away that Is $15-20 cheaper on hydro tests, but about $10 more on nitrox fills.

I have one shop who charges by the tank & another that charges by the cubic foot. Guess who fills my 120's & guess who fills my pony tanks.
 
In that case, I'll add nitrox to the list of things sciencs has been unable to dis-prove. Hmm, let's eee. We now have nitrox, the Loch Ness Monster, Bigfoot, space aliens, ...

Impossible to prove that something doesn't exist. And science doesn't give a rat's ass about Nelly, Bigfoot, or space aliens. People can debate their existence all they want, it has nothing to do with science.

My point was that the person I responded to wanted to claim that scientific studies had proven that using nitrox does not make anyone feel better after diving. This is untrue. Scientific studies may have found no correlation, for the people in the study, between use of nitrox and how those people feel after a dive. And for that reason, it's irresponsible for anyone to promote "you'll feel better" as a benefit to using nitrox.

But those scientific studies do not "prove" that nobody anywhere feels better after using nitrox. All of this is simple logic... which I do recognize is challenging for some people.
 
It also depends on the policy the boat operates. If their rule is "everyone down, everyone up", NITROX becomes a total waste of your money, since there always is at least one air hog per group. However, FL is pretty liberal, from my experience. On one dive I surfaced about 12 min after the last diver before me and no questions were asked.

Absolutely true. I've been lucky to mostly avoid those kind of dive ops (been long enough that I can't remember exactly the last time that happened to me.)
 
Completely non-scientific / anecdotal story of my experiences and beliefs.


When I was a brand new diver between 0-50 dives (aka I was a dumbass who looked like a drunk muppet in the water) I could set a timer and 60-90 minutes after I got out of the water I was going down hard for a nap whether I wanted to or not and generally felt stiff the rest of the day as well as sometimes had a mild headache at the base of my skull/neck. Switching over to breathing nitrox on my dives I definitely felt less fatigued without the stiff muscles and need to sleep right after getting home and never a headache.


Then I cranked out a few hundred dives improving my buoyancy, learned how to properly breath, and massively slowed down my final accent and now I don't feel any different at all diving air, EAN 32, EAN 50, or even 100% o2 on a dive.


It is my belief based on personal observations of myself and dive buddies, without being able to cite any actual medical studies to back it up, that I was experiencing sub-clinical DCS and that this is fairly common among new divers. The symptoms all line up rather nicely with known DCS issues and one of the freaking sales pitches for nitrox is you can up the safety margin/lower DCS risk by breathing it on an air profile.
 
If you read the study that that article was predicated on you will find that the study was very poorly designed. It was a study that was either designed by someone with a desired specific outcome or scientific incompetence. Seriously, go read the study details. Like everything in science, you need independent verification to generate a consensus. Alternatively, you can do one study tweaked a certain way and then publish the results you want to publish. There's not a lot of funding for this type of research so you can get along for years without being challenged.

Of course if you are doing dives that don't cause you to be fatigued on air.. you won't be LESS fatigued with nitrox. Which is the flaw in that study. Well, that and they didn't actually do dives - they used a chamber.

The difference in fatigue levels for me, and many others, is dramatic.

Your points are well taken. No scientific study can prove or disprove subjective feelings. I like Bourbon, fine rum, and good tequila; others like vodka and IPA beer. It is subjective. Prove that I can get satisfaction from vodka? A scientist can't. I don't like vodka or IPA beer; that's where it ends.

I dive nitrox while loosely following air profiles. I am not even close to NDL. My GF 99 and SurfGF are both ridiculously low. When we dive air, we are getting close to NDL and we have to ensure that we avoid deco.

We "feel" better because:
  1. We are more comfortable u/w not monitoring our decompression status as often while diving nitrox. To avoid deco, a bottom timer is probably all we need because we are so conservative while diving EANx. We are more relaxed.
  2. During the ascent, a richer mix helps with nitrogen washout (I admit, this is a miniscule advantage the way we dive, but advantage nonetheless).
  3. During repetitive dives, our advantage over our fellow air divers increases. They are riding NDL while we aren't close. Again, we are more relaxed.
  4. A shortened SI does not cost us BT like our fellow air divers; they are riding NDL and we aren't.
  5. Our fellow air divers are having to go shallow because of NDL issues; we go shallow to stay with the group. No NDL issues for us.
We feel that we "feel" better because we are diving almost stress free. We aren't suffering any NDL anxiety while diving with our air diver friends.

Shaving the odds of a DCS hit decreases my anxiety while u/w and on the surface. I am a member of the geriatric class after all.

Feelings are subjective. Please design a scientific study that rules-in, or rules-out "feeling" better after diving EANx verses air?

You can't do it. My "feeling" better using EANx while diving air profiles or while diving with air divers is my subjective feeling based mostly on a decrease in anxiety. EANx adds to my relaxation underwater; hence, I feel better!

cheers,
m²V2
 
...and massively slowed down my final accent and now I don't feel any different at all diving air, EAN 32, EAN 50, or even 100% o2 on a dive....

This is consistent with my experience. Ascending more slowly than a profile instructs me to & making a few extra stops on the way up, seems to leave me feeling better.
 
In that case, I'll add nitrox to the list of things sciencs has been unable to dis-prove. Hmm, let's eee. We now have nitrox, the Loch Ness Monster, Bigfoot, space aliens, ...

And Santa Claus and the Easter Bunny. These aren't myths apparently, it's just that science hasn't been able to prove they exist.
 
This is consistent with my experience. Ascending more slowly than a profile instructs me to & making a few extra stops on the way up, seems to leave me feeling better.
I feel better when they give me cold watermelon after the dive.
 

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