You're diving Nitrox: Do you choose best mix or standard mix

[King Kong Matt]

I now have spoken with a couple of people re: this topic and have received a couple of different answers. I was just wondering what you guys think about it.

Do you calculate the best mix for your profile, or do you standardize on one mix like EAN32 (assuming the profile allows)?

Why do you do what you do?

Thx,
kkm

 

[Drew Sailbum]

When I dive nitrox here, it is almost always for teaching a nitrox course. I dive an allegedly standard mix of 32%. I say allegedly because our shop buys nitrox fills from the local commercial gas supplier (as do most shops on Grand Cayman), and the mix is often off a bit.

If I have access to my own blending station, I usually choose a mix just a touch leaner than "best" mix. (I guess that may redefine "best mix" for me.)

When I dive nitrox for pleasure dives, it's because I am diving a ton that day, and I want to back off the oxygen exposure a bit. I can offgas the "extra" nitrogen quickly enough, but prefer to keep my 24 hour oxygen exposure under control.

Just my personal preference. Your milage may vary. Not valid in Puerto Rico or where prohibited by law. Prices may be higher in Alaska and Hawaii.

 

[Walter]

Best mix.

Drew is correct, there are times when best mix may be lower than 1.4.

Unless there are availability issues at your dive location, I don't see any advantage of using a "standard" mix.

 

[Rick Murchison]

Best mix is best...
(1) If you can get it
(2) If you can nail down your dive site before the boat leaves the dock
(3) If you have a bit more depth to your pockets
Otherwise, I dive whatever's in the premix bank.
Or (gasp!) air.
Rick

 

[jbm]

I have an IANTD EAN course booked for the end of April and have begun some self study, but I have yet to come across the term "best mix." Can someone please define "best mix" and explain how you determine it.

Thanks in advance; jbm

 

[kingprawn]

Most of the time I get on the boat the captain asks us where we want to go. How do you pick your mix under these conditions? I know the boat only goes out to about 100ft. So I just dive 32. Good to 110 yet good for extending bottom time. If I was more sure of the dive, I would pick best mix.

 

[Walter]

jbm,

Read pages 11 & 12 in the text.

Rick,

"If you can nail down your dive site before the boat leaves the dock"

If I can't at least narrow it down, I stay with air. If I can narrow it down to a max possible, I'll get the best mic for that depth.

"If you have a bit more depth to your pockets"

My nitrox fills cost the same regardless of what mix I get. Shops I deal with don't have nitrox banked.

kingprawn,

In that situation, EAN 32 is the best mix (although EAN 35 is 1.4 at 100 ft.).

 

[jbm]

Walter once bubbled...
jbm,

Read pages 11 & 12 in the text.

Sorry, I should have specified I have yet to receive the IANTD EAN text. At present I am working from a borrowed copy of the PADI Enriched Air Diver course. The PADI book contains no mention of " best mix" or how it is determined.


jbm

 

[Northeastwrecks]

Nitrox 32 for less than 100 feet.

Custom blend adjusted to PPO2 of 1.3 for anything over.

 

[Stone]

We can't plan our dive sites with any certainty because fishing boats may already have a claim (the depth variation is only 30 ft). I am currently mixing 32%, but as the days grow longer and we can do 3 and 4 tanks, I will be mixing more 36%.