Appeared in DIVER June 2007

John John Bantin has been a full-time professional diving writer and underwater photographer since 1990. He makes around 300 dives each year testing diving equipment.


Many divers never get to discover that their buoyancy control is really not that good. This is because finning forwards disguises the fact that they would otherwise sink. Then they take up underwater photography, need to hover and all is revealed.
Its the same with regulators. Many have compact little exhaust-Ts that put exhaled bubbles in front of your face. Dive in a press-on style, and your forward motion will put your bubbles past your ears regardless. Again, the increasing popularity of digital photography has caused manufacturers to rethink their strategy of simply making second stages as small as possible. They need to think about what happens to exhaled air.
Some divers cite the advantages of a regulator with a side-exhaust, but these inevitably have the pressure-sensing diaphragm and exhaust-valve to the side as well. Tilt your head to the right with an exhaust valve to the left, and the water that comes in as the air bubbles out reaches your mouth. The same happens if you invert most conventional-layout second stages. You get a wet breathe.
The new Aqua Lung Kronos Supreme regulator has two unique selling propositions. One is that the exhaust deflector of its second stage is cunningly designed to feed bubbles away to the side, while still retaining the dry-breathe advantages of a conventional design.
The exhaust arrangement of the Kronos is also said to help warm incoming air from the medium-pressure hose, as the exhaled air together with the heat it has drawn from your lungs passes over the finned metal heat-exchanger inline with the hose on its way to freedom.

First stage
The first stage is a balanced-diaphragm type with all the ports arranged around a fixed barrel.
A full complement of hoses can take on the layout of a Catherine wheel, but the ports are
not so close together as to require an extension piece in order to use the transmitter of a gas-integrated computer.
The Supreme version of this regulator sports an environmental kit that keeps water away from the works, so discouraging it from forming ice and affecting the mechanical operation.
The other USP of the Kronos is found at the first stage. Weve all done it at some time - hurrying to get out of our kit, we inadvertently chuck our regulator into the rinse tank with the blanking cap to the sintered filter inlet not in place.
I often see dive-centres with signs by their rinse tanks declaring that anyone who does this with a rented regulator will have to pay for a full service.
The first stage of the Kronos has a restriction that neatly avoids the inrush of water should
this happen. This Auto Closure Device (ACD) is a small thing, but it could avoid disappointment the next time you go diving, perhaps after a long interval, and with an unintentional washing of the works long forgotten.

Second stage
The pneumatically balanced second stage is quite compact. Its pressure-sensing diaphragm is at the front and a venturi dive/pre-dive control positions a vane into the otherwise unrestricted flow of air to the mouth to help prevent surface free-flows.
Cracking pressure is adjusted using the same control. This made little noticeable difference to ease of breathing at depth, and I was inclined to leave it in the pre-dive minus position.
The exhaled bubbles were routed magically away from my face when horizontal or swimming along a wall, where I tended to turn to my right to take pictures. However, when forced to swim with the reef on my left and my body oriented to look at things so that the regulator hose and exhaust port were tilted down, naturally all the bubbles came up past my face in a very uncomfortable way. Maybe well soon see a regulator with a similar long exhaust tube routed to the left.

Purge control
The purge control was unmistakable and clearly signposted, even for a heavily gloved hand.
The purge itself was progressive, and there were no sudden rushes of air to blow my tonsils down my throat.

The slightly awkward hose-routeing demanded by the ports-round-the-barrel configuration of
the first stage meant that I had to be careful when mounting the regulator on the tank so that I felt no dragging from the mouth on turning my head to the left.
Aqua Lung provides a Comfobite mouthpiece, which puts the load on your incisors rather than having to grip it with your molars.
If you dont like these, it costs little to change it for a conventional mouthpiece.
A lip guard protects your mouth from the cold or the effects of my worst marine enemy - man-eating plankton. Stinging zooplankton seem to inflict themselves just as I am about to surface.
This regulator gave me all the air I wanted at every depth. It was as good as any other regular emanating from the French Air-Liquide Empire, and that includes Apeks. It was marred only by problems associated with hose routeings.
Aqua Lung makes a wide range of first stages.
I am sure I would have enjoyed using the Kronos second stage more had it been paired with one that allowed a more sympathetic hose layout.

Divernet Divernet Divernet
Aqua Lung Kronos Supreme
COST £300
TYPES Environmentally sealed diaphragm
PORTS 4 mp/2 hp
NITROX-READY EAN 40 out-of-the-box
CONTACT, 0116 212 4200
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