Thanks to Ian Himmens and Stan Ellis and their invention of the ANSTI regulator testing machine, all regulators that you can buy in Europe now meet a minimum performance standard when it comes to the work of breathing.
This being the case, it has become something of a “pissing-contest” between manufacturers to come up with better and better performance figures, of the sort that only a piece of machinery could distinguish between.
So, given that they all now breathe easily, in which other ways might a regulator prove unsatisfactory
Recently I found myself breathing off a regulator that breathed well in static conditions but delivered as much water as it did air when I was using it in a strong current. The exhaust valve was lifting and letting water into the main chamber of the second stage.
In a strong current the flow of water across the front pressure-sensing diaphragm of the second stage can fool a regulator into thinking that you’re using it deeper than you are, resulting in an over-supply that might approach free-flow levels.
In the UK, we tend to be either out of a current within the confines of a wreck or travelling with it, so these problems don’t arise.
People who book a tropical diving holiday expecting to see pretty fish in swimming-pool conditions are sometimes shocked to discover that when there are in-currents in the channels of the Maldives, or the gaps between Indonesian islands such as Komodo, or at famous dive-sites like Palau’s Blue Corner, the flow can be enough almost to rip off your mask.
Such problems don’t arise in the static testing tank of the ANSTI machine, so it took imagination and foresight to solve this particular problem.

The Second Stage
Mares came up with the obvious-but-nobody-else-thought-of-it idea of putting the openings for the pressure-sensing diaphragm at the back of the second stage instead of around the purge control. This diver’s chin therefore protects it from the effects of fast-flowing water.
In addition, by positioning the exhaust valve at the side, Mares has made it less vulnerable to inrushes of water lifting it.
And to keep a dry breathe (a wet breathe is the curse of side-exhaust regulators) the designers angled the valve downwards, so that any water that does find its way in stays at the bottom of the second-stage cavity until it is expelled with the next exhalation.
The side-exhaust has the added advantage that exhaled bubbles don’t obscure your view when you’re stationary, as underwater photographers often are.
Even the interstage hose enters the second stage at an angle, so you don’t need such a long one. Mares uses one of those super-flexible braided hoses that are manufactured on its home turf in Italy.
The whole thing is enclosed in a soft technopolymer coating that looks as if it was smoothed over with a hot knife while still in liquid form, and it feels a lot lighter than it looks.
The purge button is a big affair for which you never have to fumble, although it works best if you press it in the middle.
Mares has not abandoned the successful aspects of its previous regulators. There is still the vortex-assisted design with the bypass tube that effectively renders knobs and venturi spoilers unnecessary, all hidden away by its super-smooth outer finish.

The First Stage
The first stage is also a new design. Called the 12S, it’s a diaphragm-type regulator with its pressure-sensing diaphragm at one end and the ports arranged around a fixed barrel.
This means that the hoses are splayed naturally, although the two high-pressure poppets were a little too close together for me to fit a Scubapro pressure transmitter alongside a Suunto transmitter.
I resorted to putting one at the end of one of the latest heavy-duty Miflex braided hp hoses. That certainly stopped it from being used as a handle!
In common with the most popular diaphragm-type regulators available today, the 12S is environmentally dry-sealed – a departure from the Mares norm.
One of the most important features of this first stage is its tri-material poppet. “The tri-material valve is composed of a central valve body manufactured in nickel-plated brass; a highly-resistant polyurethane coating covering nearly the entire valve body that can ensure elevated resistance to wear and mechanical stresses; finally, an additional covering is applied to the surface of the valve,” states Mares.
“This covering is also polyurethane but has a softer modulus to provide a perfect seal, even under extreme conditions.
“Thanks to the use of a special technology allowing for adhesion at the molecular level and the characteristics of the materials used, a high level of safety and reliability is guaranteed under any conditions.”
It claims that an uncontrollable free-flow will never occur and that a high level of reliability of performance can be expected. The unit has the typical Mares dynamic flow control.

In the Water
I was not enamoured with the mouthpiece, although it is a huge improvement on the
old-style Mares version that had all the strength and security in the mouth of a fruit gum.
However, once you compare this one with the mouthpiece supplied with an Atomic and also now many Oceanic regulators (obviously originating from the same source) lesser offerings feel like wearing somebody else’s gum-shield.
The Instinct could not give me the sublime breathe of an Atomic, which costs four times the price, but it was good enough. I did feel I needed to suck each time to inhale, but this feeling was the same at 50m as it was at 5m, so it was consistent and not depth-dependent.
I used it all week, diving up to three times a day, so it wasn’t bad enough to make me abandon it for something better.
However, one instinctively knows when something is right, and I have to say I never felt that it was completely right when compared to top-end regulators.
The purge was easy to locate with its button in the form of a flap hinged at one edge.
The Instinct comes with a DIN or A-clamp fitting and it’s remarkable that Mares can provide all these features, even if with what can only be described as satisfactory performance, at the price.

Comparable regulators to consider:
Scubapro R395 MK17, £249
Aeris Ion, £322
Aqua-Lung Kronos Supreme ACD, £340

PRICE £250
FIRST STAGE Diaphragm-type, environmentally dry-sealed
NUMBER OF PORTS 4 mp, 2 hp
SECOND STAGE Balanced, unique design layout
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