top of page
  • Writer's pictureMako

Poseidon XSTREAM regulator review

Updated: Jun 12, 2022

I don’t normally use superlatives when describing scuba diving equipment. However, I am prepared to make an exception when it comes to the Poseidon Xstream regulator.

When engineers at Swedish Poseidon gave themselves the single objective of designing and manufacturing the most reliable scuba regulator 1st-stage in the world, they drew on several decades of their own innovation experience and the superb Swedish engineering tradition promoted by industrial giants such as Volvo, Alfa Laval, ABB and many others. They also listened to the scuba diving community and sought their input. Their efforts produced the incredible Xstream scuba regulator.


In their 1st-stage valve design they used an ingenious ball arrangement resulting in the self-balancing regulator, which gives the same high performance irrespective of the pressure in the cylinder. This is achieved by automatically repositioning the valve ball ensuring that the increased upstream pressure is balanced equally with increased and counter-acting compression forces from the pressure adjustment spring, maintaining the benefits of having a perfect ball as the sealing element. Swedish design at its best. Even IKEA has reason to be envious.

In addition to this already impressive design, Poseidon engineers added TDA (Thermo Dynamic Antifreeze) protection that ensures that the through-flowing water prevents any ice formation.

The 1st-stage has 5 LP and 2 HP-ports with the DIN 5/8" tank connection.


The Xstream 2nd-stage is equally impressive. Unlike most other regulators that are downstream, the Xstream 2nd-stage is an upstream regulator. The difference between an upstream and downstream regulator is that if the downstream regulator suffered a failure in the 1st-stage it would open, resulting in a free flow. Normally, if upstream regulator fails it will close and cut the air supply. However, inventive Poseidon engineers added a safety Over Pressure Valve (OPV) onto their first stage that ensures that pressure inside the regulator will stay at a point in which the diver can breathe normally even in the unlikely event of a failure, i.e. the regulator will not free flow and it will preserve the gas supply.

The Xstream performances in terms of ease of air delivery and dry operation are almost identical whether divers swim face-up or head-down. This feature ensures great flexibility of use either on the left and right side.

As an extra bonus to this already remarkable design, the Xstream 2nd-stage is equipped with a side purge that prevents current-induced free flow and diverts bubbles away from view.


The Xstream octo is the exact same second stage that is used as the Xstream primary regulator. The only difference is the colour of the exhaust cover.


The Xstream works with air, nitrox, trimix or 100% oxygen and it is certified for use down to 200 m / 656 ft.

The US Navy Experimental Diving Unit (NEDU) has developed testing procedures that are even more rigorous than the EN 250 tests currently used by European nations. During the NEDU McMurdo Antarctic Navy testing program, the Poseidon Xstream was the only regulator that suffered no free flows in the frigid, below-freezing Antarctic waters. Of course, the Xstream complies with EN250, the requirements for diving in cold water and under ice down to 29 degrees Fahrenheit (-1.6 degrees Celsius), in line with the Norwegian Offshore Norsok U101 standard. The Xstream regulator can handle flowrates of up to 2150l/min.

Therefore, it is not surprising that the Poseidon Xstream regulator is the preferred regulator of, amongst others, the US Navy, US Coastguard, NYPD and German Armed Forces.

The Poseidon Xstream regulator is not for faint-hearted; the first stage weighs massive 768 grams and the 2nd-stage 152 grams.

When diving, your regulator is your life-support equipment, designed to keep you alive and the Xstream is nearly impossible to beat in achieving this. Its performance and reliability are extraordinary.

Whether you are a military, techie or a recreational diver, the Xstream could be described as the ultimate regulator. There would be difficult to find a better one.


bottom of page