Your dive buddy has just sucked the last gulp of air from his aluminum 80, and now he’s swimming for you.
What to do?
You’re enjoying a leisurely scuba diving down along a finger reef, soaking in the rainbow hues of its anemone carpet, when suddenly your dive buddy pops up wide-eyed from behind a nearby rock. He rockets toward you making the universal fingers-across-the-neck “out-of-air signal,” while eyeing your new titanium reg like it had his name on it.
There was a time when this would have triggered a standard buddy-breathing exercise, the back-and-forth sharing of your second stage as you and your out-of-air buddy made a controlled ascent to the surface. But today, with shorter scuba courses and less class time spent in the water, traditional buddy-breathing training is one of those skills that has pretty much fallen by the wayside. Instead, divers have come to rely on alternate air sources. When armed with an AAS, each member of the buddy team is able to have his own breathing apparatus as he makes his ascent in an out-of-air situation. This is actually much better than the old way. But in order for this system to work, everybody has to agree to carry an alternate air source.
RDC Favorites Alternate Air Regulators
Alternate air sources come in three basic types: 1) the alternate inflation regulator, or inflator reg, 2) the octopus or “safe second,” and 3) the redundant air system (RAS) which uses a cylinder and regulator completely separate from your primary air supply. In this review we’ll be looking at the first two types; for more on redundant air systems check out the RDC Special Report elsewhere in this issue.
Like the name implies, the inflator regulator is a fully-functional regulator that is integrated into your BC’s power inflator system, combining both functions into a single compact unit. An inflator reg allows you to carry an AAS without having to add another low-pressure hose to your rig, thereby streamlining your diving profile. This type of AAS also keeps the back-up reg close to your mouth and easy to reach. So when that panicky buddy comes to you begging for mercy, you can put the inflator reg in your mouth, then pass off your primary reg so you can both make it safely back to the surface to dive another day.
Inflator regulators are relatively inexpensive, easy to install and the top-end models like those spotlighted here provide surprisingly easy breathing, as good and even better than traditional octo regs. They can be connected to any first stage, just as long as the first stage’s intermediate pressure falls within the AAS’s parameters (which virtually all first stages do, but you need to make sure if you want to get top performance out of it). They are designed to be used on the standard one-inch-diameter corrugated hoses found on all modern BCs, and some even provide adaptors so you can use them with older BCs that use narrower hoses. Finally, some inflator regulators are designed to be separated from the BC’s corrugated hose so you can treat it as part of your reg system.
Inflator regs are cool because they are right there on your shoulder, always within reach. In fact, you often have your hand on it as you’re controlling descents, adjusting for buoyancy, and venting air from the BC during ascents. A piece of gear you’re continually using breeds familiarity, and that’s never a bad thing when it comes to an out-of-air situation where panic is always lurking.
The octo reg is probably the most common type of AAS breather used by recreational divers. Octo regulators are usually (but not always) less expensive than inflator regulators, and operationally they’re virtually identical to primary second stages. Most importantly, carrying an octo regulator means that if an emergency arises, you never have to take your primary reg out of your mouth. Your buddy has a problem, you hand him your octo and head for the surface. No muss, no fuss.
Carrying an octo reg does require adding another hose to your rig, and you need to come up with a place and a method for stowing it when not in use. Otherwise, it will inevitably end up trailing behind you, being dragged through bottom sand or getting snagged on everything from kelp to coral which could cause a malfunction, plus just looks sloppy.
There are two basic types of octo regulators: the traditional octo, which is a slightly modified version of a primary second stage, and those that have been designed specifically for octo use. Traditional-style octos tend to be better breathers overall (although some would argue that this is a minor point, since all octo regs breathe pretty good). Octo-specific regs are much more compact and tend to be very low-profile which makes them easy to stow when not in use. Plus, when they are needed, they are often better acclimated to air sharing due to their design and shape.
Both types come with extra-long hoses and high-viz yellow accents to make them easy to see and easy to differentiate from primary second stages. Some octo regs come with clips or other stowage accessories for securing to your BC when not being used. But since every diver tends to have his or her own ideas for stowing their gear, most octo regulator manufacturers leave stowage methods up to the individual diver.
Whatever type of octo regulator you choose, remember that its performance is dependent on the quality of the first stage it’s hooked to. Most manufacturers recommend that their octo regs be teamed to one of their own first stages. If you decide to mix brands, make sure the octo you choose has an intermediate pressure (IP) range that matches the IP of your first stage (this goes for inflator regs too). If it doesn’t, your new octo risks delivering either degraded breathing performance or unwanted free-flows. Bottom line, if you’re not sure, it’s probably best to have your dive store technician set up the rig for you.
Both inflator regs and octo regulators are proven quantities. Each offers advantages inherent to their designs, while neither really presents any major disadvantages. It’s all about what works for your particular gear setup and your diving style. You can’t go wrong either way.
Read on to get the lowdown on five prime examples of inflator regulators and five examples of octo regs, from five reg manufacturers that offer both.
Top Inflator Regulators
While not as ubiquitous as octo regs, there are still quite a few inflator regs available to divers, and we’ve tried them all. In alphabetical order, following are what we consider to be the five best models on the market. You can count on all of them to be top performers, easy to use, and each a good choice for a reliable back-up breather.
Aqua Lung Airsource 3 / QD
This pneumatically balanced backup reg is an easy breather and offers lots of convenience features. First is the Trim Grip, a reinforced hand-hold halfway up the corrugated hose that provides a grab point so you can activate the BC’s pull dump while you’ve got the Airsource 3 in your mouth. Also, Aqua Lung gives you a choice of buying the Airsource 3 with either a standard quick-disconnect coupler or a permanent screw-down fitting similar to the one used on a standard second stage. This permanent connection keeps sand, salt and corrosive moisture from getting into the mechanism.
Included in this version is an in-line shut-off valve to cut off airflow to the inflator reg in the event of a malfunction. Finally, you can separate the Airsource 3 from the BC by disconnecting the corrugated hose at the Trim Grip; half of the hose and the Airsource 3 go with your reg rig for cleaning and storage, the other half stays with the BC.
The Airsource 3 offers a lot of choices. It’s also the only inflator regulator of this group that’s sold with its own corrugated hose. The assembly screws right onto any Aqua Lung or Seaquest BC, and adaptor rings are available for use on BCs by Mares, Scubapro and Zeagle. (While we’ve haven’t checked this out for ourselves, word is that these adaptors work on other brands too.)
Atomic Aquatics SS1
The SS1 is a quality AAS. Made with 316 stainless-steel and titanium internal parts, it comes with the patented Seat Saving Orifice that’s found on all Atomic second stages which helps to explain its two-year/300-dive service interval. This pneumatically balanced backup breather is one of the smoothest, driest inflator regs we used. Performance-wise, it behaves much like a top-end second stage. For pure ease of breathing it took first place among this group of inflator/regs in our blind breathing tests. It’s also easy to use; inflate and deflate buttons are large and contoured, which enables your fingers to tell them apart without having to look at them. After the dive, a threaded coupling lets you unscrew the SS1 from the end of the corrugated hose so you can keep it with your regulator and gauges, or easily transfer it if you have more than one BC. It’s set up to be used on a standard ne-inch-diameter corrugated hose, but comes with a set of adaptors to fit virtually any BC hose size, along with various-sized stainless-steel pins for hooking up the cable to activate the BC’s pull-dump exhaust valve.
The SS1 is designed to replace a standard octo and streamline your rig, but performance-wise, it may just overshadow your primary second stage. It’s a little pricey, but it’s worth it. Available in six colors, in stainless-steel and all-titanium versions (the titanium version is lighter and provides added corrosion resistance).
Mares Air Control
The Air Control is the new kid in this group of inflator regs, but it comes to the party with a well-thought-out design and a number of performance and convenience features. Like on most of Mares’ primary reg systems, the Air Control is equipped with a few Mares exclusives, like VAD (Vortex Assisted Design) and DFC (Dynamic Flow Control), which, respectively, is an airflow system to increase inhalation sensitivity, and a system to minimize first stage pressure drop and inhalation resistance. It also is fitted with a Mesh Grid purge cover to help prevent free-flows, a big plus for a backup breather that spends very little of its time actually in the diver’s mouth. To make life easy the air control apartAir Control disconnects from the corrugated hose so it can be cleaned, serviced and stowed along with your reg system. It’s a bayonet-style push and twist coupler that comes with three adaptors to fit virtually any-sized corrugated hose.
This is a nice backup breather. The different-sized textured buttons make for easy finger recognition, even when wearing gloves. The angle of the mouthpiece and its size and shape are intended to allow you to hold it comfortably in your mouth. And the fact that the unit can be separated from the BC for cleaning and storage is just another bonus.
Whereas the Mares Air Control is new to the alternate air source scene, Scubapro’s inflator reg has been around since the beginning. Introduced over 30 years ago, the Scubapro Air was the original integrated inflator reg. Now in its fourth or fifth generation, the Air2 continues to be a strong contender in the performance arena. Delivering smooth and steady airflow, it offers big ergonomic control buttons that are easily recognizable by touch, a soft full-cover purge and an orthodontic mouthpiece. A fixed VIVA (Venturi Initiated Vacuum Assist) flow vane has been added to the mechanism to prevent free-flows. The purge is super powerful, making easy work of clearing water from the mouthpiece. Speaking of mouthpieces, this one is on the small side but it sits comfortably in the mouth and the generous tabs give your teeth something to bite down on. The Air2 permanently mounts to any BC with a one-inch diameter corrugated hose.
The Air2 has been and still is a solid alternate air source and a pack-leader when it comes to performance. It’s hard to beat it for easy-breathing; in our blind breathing test it came in a strong second. Combine its performance and its lineage with one of the lowest prices in this group, and you’ve got yourself a keeper.
For pure performance the Gemini runs with the best of them. As a power inflator it fits nicely in the hand and offers responsive, well-placed buttons that are sized and shaped for easy touch recognition. As a backup breather it delivers reliable airflow with minimal inhalation effort. It comes with a forceful full-cover purge that makes easy work of clearing water from the unit before passing your primary to a buddy, and the mouthpiece, while a tad small, is well-shaped for easy gripping, so you don’t have to worry about it popping out of your mouth while you’re concentrating on getting yourself and your buddy safely to the surface. The unit permanently mounts on to any BC with a one-inch-diameter corrugated hose.
The Gemini is the least expensive of this group but delivers some of the best performance, both as a power inflator and as a backup breather. It rates high for simplicity of design, ease of use, and above-average breathing.
Top Octo Regulators
There are a lot more octo regulators on the market than the five that follow, and most of them are pretty good safe-seconds. However, they all approach their backup breather roles a little bit differently. So rather than flood this page with dozens of models that are virtually identical, we decided to spotlight octos that we know well and that each represent a slightly different take on the octo concept.
Aqua Lung Calypso/Titan Octo – It’s Convertible
For divers who want to run their octo off their left side, or who want to make it so they can buddy-breathe without having to face each other, the Calypso/Titan can be easily converted so that the low-pressure hose comes out of the left side of the casing rather than the traditional right side. However, this also involves switching the VAS (vane adjustment switch) from left to right, so it needs to be done by an authorized Aqua Lung reg technician. The Calypso/Titan octo is nothing if not high-viz, it’s an easy breather and the soft full-cover purge clears the mouthpiece quickly. The VAS helps prevent free-flows when the octo is not being used.
Versatile, simple to use, a smooth dry breather, and reasonably priced. Enough said.
Atomic Aquatics Z2 Octo – High Performance
You won’t find a higher performing octo than the Z2 Octo, simply because this pneumatically balanced backup breather is virtually the same reg as the standard Z2, which for years has blown the doors off virtually every mid-priced reg on the market, along with quite a few of the platinum-priced models. So the fact that it was the hands-down best performer in our blind breathing tests came as no surprise. The Z2 is made with 316 stainless steel and titanium internal components along with zirconium-plated brass. It features Automatic Flow Control and Atomic’s patented Seat Saving Orifice that helps prolong second stage seat life. The octo requires virtually no maintenance and in fact comes with Atomic’s two-year/300-dive service interval.
You simply can’t go wrong with the Z2, whether you’re using it as a backup breather or a primary breather. In fact, the only downside (if you want to call it that) to the Z2 Octo is that it doesn’t look like an octo. With a 36-inch black LP hose and only a hint of yellow accents on the cover, it looks more like a primary second than a safe second.
Mares Octopus MV – No Down Side
The Octopus MV is the only octo in this group, and the only octo in Mares’ reg line, that was designed specifically for duty as a safe second. You don’t need to be convertible with the Octopus MV because it has no upside-down position. The exhaust valve is positioned to the side of the mouthpiece rather behind it, so you can use it from the mares octo2right or the left, either way works. The Octopus MV is long and thin rather than round so it is pretty compact and stows easily. Though designed specifically for octo duty, it still comes with a number of Mares design perks, including the VAD (Vortex Assisted Design), an airflow system to increase inhalation sensitivity. It also comes with a mouthpiece plug with a molded eye for clipping the reg on a BC D-ring, a nice extra.
This little octo is compact, versatile, and sports a pretty good price. It’s got a rather weak purge but offers some pretty good breathing for its size
Scubapro C200 Octo – Full-Featured
The C200 Octo was added to Scubapro’s reg line just this year and it offers a lot of standard goodies plus a number of extras. First, it’s full sized with lots of high-viz yellow to attract attention. It comes with a very effective VIVA (Venturi Initiated Vacuum Assist) switch for controlling free-flows. Its orthodontic mouthpiece is sized and shaped so you can get a good hold of it without stressing your jaw muscles. It also comes with a OFD (Optimal Flow Design) valve for improving breathing performance, and a mouthpiece clamp with clip for attaching the octo to a BC D-ring.
The C200 is one of the more expensive backup breathers in this group, but it offers a lot for the money.
Sherwood Octo – Simple & Steady
The Sherwood Octo is a new entry in the octo market but its performance bonafides have already been established. Virtually identical to the Magnum (without the flow control lever), the Sherwood Octo sports a sharp-looking oval-shaped casing with a bright yellow full-cover purge. It’s a sweet breather; among this group of octos it came in second in RDC’s blind breathing tests for pure ease of breathing. But it’s also a steady breather; you don’t have to worry about a frisky reg on the edge of a free-flow when it’s clipped to your side. It’s also comes with a pretty good mouthpiece.
The Sherwood Octo is your basic backup reg, delivering rock-solid performance and the lowest price tag in this group. Not a bad combination.
I’ve been a diving addict since my 14th birthday when my parents took me to the Bahamas and had my first scuba diving experience. I’ve been an active diver ever since but in the last few years my focus shifted on sharing my thoughts and experience on diving gear, writing product reviews and gave up on organizing dive tours.