Hi SD fans, and welcome back. Nitrox. Enriched Air. The devil gas.
Whatever you call it, nitrox is now a staple on the scuba diving scene, and in this video,
I’ll be telling you why being certified to use this gas is a must for all divers.
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Oxygen enriched air – or nitrox, as it is more commonly known – is now a staple on
the recreational diving scene, but it isn’t that long ago that it was once only used by technical
divers, and even then, was still widely regarded as ‘devil gas’ by old-school divers who thought
good old compressed air was all anyone needed and why would you want this new-fangled mixed stuff.
How things have changed – it is now among the most-popular specialty courses
of all of the major training agencies. Yet I still see,
and here, people who have this baseless fear of diving nitrox.
Let’s start with what nitrox is. Essentially, it is a mix of nitrogen and oxygen.
Take a deep breath. Clean, fresh air – right? Well that inhalation filled your lungs with
a mix of 21 percent oxygen and 79 percent nitrogen, so you are breathing nitrox right now.
However, in the diving realm, at least in the world of recreational diving, nitrox is typically
attributed to the most-common oxygen-enriched mixes of 32 percent and 36 percent, although the
former is the blend you will most-commonly encounter out in the big wide world.
So-called recreational nitrox is basically any mix from 21 percent to 40 percent. Beyond that you are
in the realms of technical diving. I am staying in the world of recreational diving in this video.
So, why dive a tank of 32 percent nitrox? Well, cast your mind back to your entry-level diving
course. You’ll recall that it is the nitrogen in what you are breathing that dictates how long you
can stay at a certain depth before having to make your ascent back into the shallows. So, by diving
a mix that has more oxygen and less nitrogen, this means that you can extend your bottom time,
especially on repetitive dives, and we all want to spend more time under the water, don’t we?
Say you were diving to 70ft. On air, your NDL will be around 40 minutes.
On 32 percent nitrox, you are looking at around 60 minutes. Massive difference.
Want more clarity? The best way to describe this benefit is with an example dive.
The Thistlegorm shipwreck in the Egyptian Red Sea is one of the world’s greatest wreck dives.
It is like an underwater museum, with its cargo holds chock full of motorcycles,
ammunition, trucks, rubber boots, airplane parts and much more dating from World War Two. It lies
in around 100ft of water and is the perfect wreck for a nitrox dive, because believe me,
you will want to spend as long mooching about exploring as possible. On the first dive, if you
are diving nitrox, you will get several minutes more no decompression limit than those diving air,
but it is on dive number two – and beyond – that the difference becomes more apparent.
On dive two on the Thistlegorm, you can be waving bye to the air-diving buddy teams in your group
a good 30 minutes or more before you get near to your NDL on nitrox. This is huge.
Over and above this defining point, there are many reasons to dive nitrox.
Some people insist they feel better, more alert and less fatigued after a dive on nitrox over a
dive on compressed air. There doesn’t seem to be any scientific proof on why this should be,
and I have heard many instructors dismiss it as being ‘just in their head’,
but heh, if you dive on nitrox and feel better after a dive, whatever the reason, go for it.
I have also seen many a diver who seems to be purely using nitrox so they look
‘techie’. I am sure you will have seen them. They swan about on the boat, usually waffling
about epic dives they have done, have a multi-mix full-on technical dive computer – or two – and
then when they actually get in the water, they bimble about in 30ft of water and blitz through
their gas supply in 30 minutes. I have nothing against these people – these ‘wannabe techies’,
as I call them, buy all the tech gear, so that is good for the manufacturers, and if they are paying
for nitrox for all their dives, then it is good for the dive centres as well! Winner all round.
Then there are those who, for whatever reason, want to build in a safety margin on their dives.
They might be older, and not wanting to put undue stress on their bodies,
or maybe they have previously had some dive-related issue and are playing safe.
Whatever the reason, they will dive with a 32 percent nitrox mix but leave their dive
computer set to air mode. Thus, when they reach their NDL and begin their ascent, in reality,
they are well within the actual no-deco limit of their chosen gas. This means they massively reduce
the amount of nitrogen being absorbed by their bodies. The only caveat with that is to ensure you
do not inadvertently exceed the maximum operating depth of your nitrox mix. I have seen people deal
with that by diving with two computers, one set on nitrox and one set on air, but to me,
this is just adding in confusing elements you don’t need to be dealing with on a dive.
Talking of MOD, that brings me nicely on to one of the common misconceptions about nitrox.
Too many times I hear people say ‘I don’t need to dive nitrox as I am not going deep’.
Nitrox is not a deep-diving gas. As I said earlier, I am only dealing with recreational
mixes here, but even 32 percent has an MOD of around 110ft, which is well within the commonly
referenced recreational depth limit of 130ft. The higher the oxygen content, the shallower the MOD.
However, what nitrox does is allow you to spend more of your precious dive time on the deeper
elements of your dive, as I clearly showed in the Thistlegorm example. I did a liveaboard
in Sudan back in 2007, and was extremely glad to be diving nitrox, as all of the sharks were
milling around at 100ft plus, and so I wanted to spend as much time with them as possible,
and the extended bottom time afforded by my nitrox mix was much appreciated.
I have also heard people saying they get longer dive times on nitrox. Again,
not strictly true – yes, you may be able to spend longer at the deeper portions of your dive,
but you will consume your nitrox mix just as quickly as you do compressed air.
So if you drain a tank in 25 minutes, it doesn’t matter what is in there,
you will be back on the boat at that time. Nitrox is not some magical cure all for being an air hog.
So why don’t people dive on nitrox? Well, there are still some of the old guard who
think compressed air is where it is at, and they aren’t breathing some fancy mixed gas,
but thankfully this breed is dying out. I have heard dayboat divers say they aren’t
diving nitrox as they don’t want to pay a premium over normal compressed air fills.
Now depending on where you are in the world, this is not typically more than a few dollars more per
tank, and when you consider how much money people will have invested in their dive kit in the first
place, not to mention their place on the boat that day, it seems bizarre to me they won’t
chuck in an extra $20 or so for a gas that will allow them to enjoy more time under the water.
The ones I really cannot fathom are the people who have paid hundreds, even thousands of pounds,
to go on a diving holiday and then resist paying $100 for a nitrox package during their stay. After
spending all of that money in the first place, why would you not do this? Not only do you get
to spend more time underwater, but you are also safer, as you are seriously reducing the amount
of nitrogen being absorbed by your body over the course of the repetitive dives on the trip.
One more thing. If you are diving with a centre that can do custom nitrox mixes
rather than just churn out 32 percent, consider the dive site you will be visiting
and what mixes will work the best. When I dived the Oriskany aircraft carrier out of Pensacola
in Florida, I was with MBT Divers, and they were happy to do whatever mix you wanted.
We were doing a three-tank dive on the aircraft carrier, and as I had dived it several times
before, I knew all of the dives would be centred around the main superstructure. At the time,
the flight deck was at around 135ft, and the top of the superstructure was around 60ft, though it
has settled into the silt and is now quite a bit deeper. I opted for a 28 percent, a 32 percent and
a 36 percent set of tanks. Most of the people on the boat just had three 32 percent tanks each.
They couldn’t understand why I had different mixes, but I had a dive plan. Dive one I used
the 28 percent, which allowed me to thoroughly explore the bottom couple of deck levels before
making my ascent. Dive two I used the 32 percent and concentrated on the middle deck levels,
and for dive three, I used the 36 percent and focused on the remaining couple of decks to the
top of the smokestack. I ended up having much longer on the wreck on dives two and especially
dive three because of using nitrox mixes which were better suited for the dives I was doing.
At this precise moment in time, dive travel – well, travel in general, to be honest – is still
reeling from the COVID-19 pandemic, but things are slowly improving, with more and more countries
starting to open up their borders and some semblance of normality peeking over the horizon.
You might be diving in your own country, or you might be waiting anxiously for that first trip
abroad. If you are not already nitrox certified, now is the perfect time to do it. Many training
agencies offer the nitrox specialty as an online course, so you can complete it in the
comfort of your own home and be ready to reap the benefits on your next trip, wherever that may be.
Many dive centres, and especially liveaboards, now offer free nitrox to certified divers
during their stay or time onboard, and why would you want to turn that bonus down? Do
yourself a favour and get nitrox certified, whatever your current level of qualification,
if you haven’t already got your ticket. You know it makes sense.
Do you dive nitrox? Why do you use an enriched oxygen mix for your diving? Leave your comments
below, and if you have a question, fire away – if we can’t answer, maybe someone in our community
will be able to. Remember, if you enjoyed this video, be sure to subscribe to our
YouTube Channel, and check out our playlist for more inspirational and educational content.
As always, stay safe – and if you are going diving soon, enjoy!