SCUBA MYTHBUSTER – The Great Nitrox Myth

Vance Harlow’s book “Oxygen Hacker’s Companion” (Airspeed Press) speaks of nitrox and gas mixing as a modern day dark art. In the introduction he claims that “dive shops and gas suppliers are both well aware of this mystique, often as not seem to enjoy their role as initiates of a discipline which is shrouded in mystery, and are often reluctant to share information. In our investigation we found a great deal of truth to this and answers as to why you may be burning more vehicle gas to get your breathing gas from a not so local dive shop. We also uncovered why this myth may also be causing dive shop owners to unknowingly send prime, higher-spending divers to the competitor’s shops and taking a pass on higher gross sales; not a good business plan during these hard economic times.

Our investigation started close to home and at the peak of gas prices. We grumble and wondered as we passed by local dive shops and drove over an hour and half to get our nitrox fills. The mass of divers today are baby boomer divers are aging and aging divers are finding love in the O2 bottle. Additionally, nitrox use is growing among all divers. So as divers we asked, why won’t more shops get nitrox? But since dive shops are a business, maybe it is better to first ask, why a shop should consider adding nitrox. The good reasons we list below all can be lumped into a great business case that yields more customers that spend more money in your shop.

  • Nitrox divers dive more often and fill more often.
  • Average Nitrox fill fees are twice that for an air fill
  • Nitrox certification classes bring in around of $125 per student plus materials can be $60.
  • Advanced nitrox classes add even more to the teaching revenue stream.
  • Nitrox is one of the gateway classes to even more advanced classes.
  • Oxygen analyzers at around $200-400
  • Nitrox conversion of cylinders at around $30 – $60 per cylinder
  • Nitrox divers spend more money. They buy more gear and more expensive gear than air divers (e.g. higher priced computers, wings, tech and semi-tech level gear, pony tanks)
  • If you have nitrox, these divers will spend money at your shop and not buy equipment from the other shop where they get their nitrox fills.


After Chaela and I became nitrox certified we no longer went to our local dive shop for anything. In fact we passed by the three closest dive shops to get our nitrox fills. Initially, we even went to a shop with an owner that we really disliked and purchased equipment from him because we were browsing the racks waiting for our nitrox fills. We later found a friendlier dive shop with nitrox, but it was 50 minutes drive each way. During the first year of being nitrox divers we spent around $8000 in equipment upgrades including custom DUI drysuits, DiveRite TransPacs, wings and pony bottle setup. On top of that, we filled our tanks with nitrox over 120 times (another $1000 to the shop’s gross). During that same period of time our initial and closest local dive shop did not get our $9000 and most surely lost sales from other local nitrox divers that did not shop there. That same no-nitrox shop downsized from a two-storefront shop to a one storefront shop 8 months ago. And two months ago, again downsized. Today they are a tiny shop that now literally occupies a former bathroom of their original space and still only fills air. So why do they not add a nitrox option. Because in summary of the owner’s words, “A nitrox system way too expensive, too complicated, requires highly trained staff, dangerous, and only a membrane system any good.” All myths.

WHY? The crux of the myth.

We polled dozens of dive shop owners of non-nitrox shops and asked them why they do not have nitrox. Like the shop in the story above, almost across the board the answer was (expected) cost. So we asked them, “How much do you think it would cost to go from your current air system to a fully functional continuous mixing nitrox system (the mid range of style of nitrox systems)? The wild guesses and crazy estimates we heard were not even close. The range that gave was between $10,000 and $35,000. Even after we made sure they understood that we meant that system was only an add-on to their current compressor system and for the mid-range continuous mixing system, the estimates remained the same. These were not novices of the industry. They were dive shop owners that have been in the business for years and most were off by double digit multipliers. One shop owner and charter operator that was already selling nitrox fills via the lower cost partial pressure mixing guessed it would be $12,000 for him to move to continuous mixing. Dive resorts and charter boats are equally likely to be lost in the fog of the nitrox myth.

So how much does it really cost? We found many helpful nitrox shop owners, like Mark Peil from Hudson Point Dive, that were willing to tell us the actual amounts that spent for the full conversion to nitrox. These actual prices ranged from only a few hundred dollars to $3200. If you are smart do-it-yourself you can use the Vance Harlow’s book, “Oxygen Hackers Companion” to build a very inexpensive yet safe and accurate system yourself. Ron Ault of Hood Sport ‘N Dive, is about as close a scuba Zen master as I have seen and who spent years mixing gasses in the Naval Experimental Dive unit, said he has installed full systems for other dive shops for $800 dollars which included parts, labor, travel and dinner. Richard Boyd of Global Mfg. Corp (GMC) pointed us to complete ready to use packaged systems with mixers and valves and analyzers for under $3000. The ongoing costs of offering nitrox are low also. The bulk of your cost is oxygen supplies which at around $20 to $30 for 250 cu ft tank, are easily covered by the increase in sales prices for nitrox fills. It is easy to find a local gas supplier to deliver your Oxygen bottles on a lease or purchase plan.

If the shop owner does go the aforementioned do-it-yourself and the costs really plummet. The nitrox mixing stick can be made from piece of plastic pipe and some a bunch of end caps. You can even build your own O2 analyzer for around $100 with radio shack parts. The parts cost for a complete package with two analyzers, and good regulator is only around $300. Some independent divers are finding the systems so economical and easy that they are cutting the fill-umbilical cord to dive shop altogether and buying a home or portable compressor and adding a home built nitrox mixer. Scott Boyd has photos and quick guide on how to build a mixing stick at

In addition to the price myth, a few shop owners claimed that they would have to spend too much on training and certifications for all of their staff. The extra training necessary for serving nitrox is minimal and easy for anyone qualified to fill air. If you spend a bit more on some dedicated nitrox cascade tanks (about $300 each) you can premix and bank the popular 32% nitrox, which makes it as easy and fast as filling air.

Some shops think they are going the cheapest route by using the more complicated partial pressure mixing (PPM). However, Steven Lindblom of AirSpreed Press says it’s not a good plan for many reasons. PPM requires much more training, takes longer, and it is too easy to slip into a pattern of filling with dangerously high pressures of oxygen. Also, most shops doing PPM add on a $1200+ hyper-filter. But you can save that money and put the $1200 into the easier and safer continuous mixing system.

If you have a dive boat or want to fill nitrox without any oxygen tanks you can still get into the higher end membrane system for less than many shop owners thought you needed to spend for cheaper methods. Membrane systems, according to Richard Boyd of GMG start at around $5000. When we mentioned membrane systems to Steve Lindblom, he cautioned that it is not too difficult to over pressurize a membrane and defile it.


So if you regularly drive past a perfectly good dive shop or pass on a nice diver resort because they do not offer nitrox, show them a print out or send them a link to this article ( Better still, join a the larger movement and encourage the editor at your favorite dive magazine to print this or another article to that will help dissolve the NITROX MYTH once and for all.