A little about regulators

Let Dive Now Whangarei help explain how to choose a regulator set?

What is a Regulator?

Its job is quite simple, get the air from your cylinder to your mouth.  Well it’s a bit trickier than that as the air in your tank is pressurised and so the pressure needs reducing to a point where you can breathe it comfortably.  This happens in guess how many stages? Two.  That’s how we get the names First stage and Second stage. Each one reduces the pressure.

What are the choices?

Unbalanced vs Balanced vs Overbalanced

Basically this refers to the ease of breathing as you go deeper.  With the ambient pressure of the water adding up as you go deeper, (1 atm per 10 metres) and as the air in the tank gets lower, the demand on your breathing will increase and get harder.

 Unbalanced regulators are great in the shallows, they get harder to breath from as you get deeper and your gas supply gets used up.  But they are simpler in design and therefore cheaper. 

Balanced regulators “balance” with the ambient pressure and so breathe just as easily at depth as they do in the shallows.  They are more complex and so cost more.

Overbalanced regulators will work even better at depth than a balanced regulator. More complex and so cost more. 

For a more technical explanation ask Dr Google or our service technician Graeme.

Number of HP (High Pressure) points

This is where you SPG (Submergible Pressure Gauge) plugs in. Well if you are using a transmitter, then you will want a second HP point.  Even with a transmitter, it’s best practise to run a small SPG as back up that is clipped onto your BCD out of the way, just in case you have a battery issue in either transmitter or computer.

Number of LP (Low Pressure points)

  • Primary Second stage
  • Back up (Octi) second Stage
  • BCD inflator
  • Drysuit inflator

More hose routing options with multiple ports.

Fixed position or turret

More hose routing options again.  For single tank, stage bottle or twin tank diving.  The movement in the turret can help when we turn our heads to prevent the regs being pulled from our mouths.

Environmentally Sealed

Prevents water and contaminants entering your first stage.  Great for the diver who cannot rinse/soak their gear immediately or for divers diving in fine silty conditions found in some wrecks and cave systems.  Also for divers diving contaminated waters.

DIN or Yoke (open face)

DIN screw in giving a lower profile and an O ring that is protected inside the cylinder valve.

Open face, generally more common in NZ and are slightly easier to put on.

Adjustable Venturi

Pre Dive adjustment to prevent sensitive regulators from free flowing.  Great on Octi’s.  You can still breathe from them when in the Pre Dive mode if you forget to turn them to Dive mode.

Adjustable work of breathing

As crazy as it sounds, some people like to feel the effort of the reg making them breathe.  For divers going on an overseas trip where they will not have access to their favourite scuba technician, then it is piece of mind.  If you start to get a bit of a free flow from your reg, intead of it ruining your trip, you can dial it back just enough to make it stop.  It will get you through your holiday and then you can bring your regs in for a service.

Plastic vs Metal vs Carbon

Plastic has that cheap feel and it also can become brittle over time.  There are different qualities of plastic, but cheaper models with full plastic purge covers usually need the covers replaced regularly.

Internals made of plastic will eventually crack and need replacing. 

Metal will last much longer and has a much better heat exchange rate so allows better performance.

Carbon fibre faceplates really make little difference.  They are physically lighter, but as it is already such a small area, will you notice it?  (Scubapro A700 faceplate carbon 10g vs metal 42g).  Carbon fibre flexes back to shape, so if dropped it should take the impact.

Carbon does look pretty though......

Handmade options

Like Scubapro’s A700, it’s nice to know that you have the quality of a handmade casing, barrel and faceplate.

Cold Water or Warm water rating

What is cold water when we are talking scuba?  Well anything colder than 10°C.

Regulators which are not designed for cold water use are marked with ‘>10°C’ on both the Second Stage and First Stage.  The risk is from freezing, not neccesarily from the water, but from the temperature drop of the expanding gas coming out of the hose. 

Performance when it counts, industry standards.


EN250A is a Europeon Standard that tests the 1st stage with a demand on the primary and alternate demand valve to simulate two divers breathing off a single 1st stage as deep as 30m.  If the 1st stage can deliver gas to two 2nd stages it will have EN250A stamped somewhere on it.  

EN250A >10°C

With the new EN250:2014 regulators that are not designed for cold water will have to have to be marked with “>10°C” somewhere on the 1st and 2nd stages.  'Cold Water' is defined as water temperature below 10°C, and regulators marked with EN250A are tested to a temperature of 4°C. Smaller, lighter regulators do not have enough metal parts to act as a heat sync and absorb heat from the water to prevent icing up in cold waters so it should only be used in warmer waters. 

“Apeks recognises that emergencies can happen beyond these limits and we are the first regulator manufacturer in the world to design, have independently tested and be awarded CE approval for alternate air source products which far exceed the minimum requirements of EN250:2014 including Annex A. This means that an Apeks alternate air source matches the performance of the primary demand regulator that it is intended to work with, tested to depths of 50 metres (164ft) and in water temperatures below 10°C (50°F) where stated”.

The MK25 EVO regulator uses Scubapro'snew Extended Thermal Insulating System (XTIS). The Scubapro MK25 EVO first stage regulator meets the new EN250-2014 requirements for cold water diving, CE approved for 3360psi (230 bars). This model goes even beyond this super stringent qualification and has successfully been tested in extreme cold diving conditions at less than 36°F (2.2°C). The freezing resistance has been increased by 30% over the previous MK25 regulator first stage. Scubapro has achieved this with some new design features.

Octi or combined Octi with inflator mechanism

What is an Octi?

An Octi or Alternate air is a back up second stage regulator to be used in an emergency by either a diver sharing air with another diver or by a diver whose primary regulator is malfunctioning.  They are like airbags, we hope to never use them.

They are also used to inflate lift bags and some dSMB’s.

Not having an Octi

Diving without an Alternate Air (octi) is a bit of a selfish option.  If you have a problem with your regulator, you run the risk of not having the tools to get safely back to the surface to your friends and family. 

If your buddy or just another diver needs air, offering your alternate air, getting them calm and surfacing is a controlled event.  Without the alternate air, the only option would be to buddy breathe.  This was removed from diver training many years ago to simplify the out of air procedure, as it is a very difficult exercise to do whilst relaxed and planned.  Add the stress of the situation and the rapid breathing of an unhappy diver and the risks escalate. 

People breathe at different rates and so whilst one person would be waiting comfortably for their turn to breathe, another would be turning blue running out of Oxygen in their body.

Combined Octi/Inflator mechanism

Your BCD inflator mechanism is pretty simple.  By adding your back up regulator to it, you are complicating it.  Service technicians who service your scuba,  generally aren't big fans of them as it is one device doing two jobs, so carries a greater risk of malfunction.  Tuning them is also slightly more problematic.

With the Octi/inflator you have a heavier bulkier inflator.  In the event of sharing air, your hose that you donate will be quite short.

On the plus side, it is one less hose to stream line.  The can fall out of the clip and if you or your buddy aren’t aware, it can get dragged around the reef and snagged, get damaged or damage the reef.

Necklass/long hose vs standard Octi

Some divers have the back up on a very short hose that is necklaced around their neck.  They then donate the regulator that they are breathing off of which is a longer hose than standard.  About 2 metres long. 

This means you have to stow it correctly so it doesn’t snag, but it gives the diver receiving your air more room to manoeuvre whilst aborting the dive..