Frequently Asked Questions 

If you have any questions about your Poseidon products, you may be able to find the answer on this page. If you still have any questions, feel free to contact us directly
Questions about the M28 Computer? Click here to go to the Q&A section of the Poseidon Rebreather website. 
Q: I have noticed a loud whistling noise coming from the 1st stage on my Xstream regulator, when breathing in it. What is causing this and is it dangerous? 
A: A whistling noise can sometimes be heard when the Xstream first stage is pressurized or depressurized. This is due to a resonance frequency which takes place between the ball bearing and the actuating pin. This noise should however not be detectable during low flow rates such as while breathing. The noise has absolutely no effect on the regulator functionality. In most cases, the noise can be removed by turning the actuating pin a quarter turn. Contact your nearest Poseidon service center and they can help you with this. 
Q: How long is the warranty period on a new Poseidon product? 
A: When you buy a new Poseidon product, it comes with a 24 month factory warranty, except those that are regarded as consumables. 
Q: How often do I need to service my Poseidon regulator? 
A: It depends on how much you dive. If you dive 40 - 50 dives a year, we recommend that you service your regulator once every 24 months. 
If you dive more than that, you should service it once every year. 
Those that dive every day, should have it serviced at least once every 6 months or so. 
Remember that your regulator is life support equipment, designed to keep you alive. If you don't maintain your regulator, it could cause a failure of the equipment. 
Q: Can I use a Cyklon, Jetstream or Xstream Deep regulator with nitrox? 
A: Xstream Deep, Cyklon X and Jetstream Mk3 manufactured after 2015-01-01 are all Nitrox ready from the factory and can be dived with using a maximum of EAN 40. Older Xstream Deep, Cyklon 5000 and Jetstream are not Nitrox ready and can only dived with gas containing a max of 21% oxygen. 
Q: What Poseidon 2nd stages can I combine with what Poseidon Octopus? 
A: You can mix Jetstream and Xstream 2nd stages/octopus on the same 1st stage, as these two 2nd stages work with the same intermediate pressure. 
But you can NOT mix a Jetstream or Xstream 2nd stage with a Cyklon 2nd stage/octopus. The reason is that the Cyklon 2nd stage works on a higher intermediate pressure than the Jetstream and Xstream 2nd stages. 
Mixing Jetstream/Xstream 2nd stages with a Cyklon 2nd stage can be dangerous! 
Q: What´s the intermediate pressure on Poseidon regulators? 
A: The Jetstream and Xstream regulators should be set to 8.5 bar (123 psi) intermediate pressure, at full tank pressure. 
The Cyklon 5000 regulator works at an intermediate pressure of 11,5 bar (166 psi) at 20 bar (290 psi) tank pressure. 
Q: Can I use a standard 9/16 LP hose on my Poseidon regulator? 
A: If the 1st stage you have, has an over pressure valve built in to it, or has an external over pressure valve attached to a LP port, you can use a standard 9/16 LP hose, if it fits on the 2nd stage connection. 
For the Jetstream and Xstream 2nd stages, there is an adaptor available, that allows you to connect a standard 9/16 LP hose to the 2nd stage. 
Q: If I put a Cyklon 2nd stage on a Triton 1st stage, do I need to modify the Triton 1st stage in any way? 
A: The simple answer is no. 
All you need to do, is to adjust the 1st stage to the correct intermediate pressure that the 2nd stage works at. 
Q: Why won´t a LP hose fit in the LP port of my old Cyklon 1st stage? 
A: On older Cyklon 1st stages, the standard thread size of all ports were 1/8. 
Today, all LP ports are 3/8 and all HP ports are 7/16 sized. 
If you have an older style 1st stage, there are adaptors that can be used, so you can attach standard sized hoses to your 1st stage. 
Male 1/8 --> female 3/8 thread (Article number 2415) 
Male 1/8 --> female 7/16 thread (Article number 2910) 
Q: What 1st stages can I use the Atmosphere Full Face Mask with? 
A: The Atmosphere FFM is CE approved together with the Xstream 1st stage and it's with this 1st stage the mask performs best. 
If you intend to use the Atmosphere FFM with another 1st stage, make sure that the correct intermediate pressure is used. 
Q: My Atmosphere FFM is vibrating when I breath through it. How can I resolve this? 
A: Most likely, you have your FFM connected to a non-Xstream 1st stage or the intermediate pressure on your 1st stage is not correct for the Atmosphere FFM. 
Q: Can I put a standard Jetstream 2nd stage on an Atmosphere FFM? 
A: The Jetstream PP (the Atmosphere´s 2nd stage) is a modified Jetstream 2nd stage which is constructed to work in conjunction with over-pressure and hold low CO2 levels inside the face mask. Thus you can NOT put a standard Jetstream 2nd stage on an Atmosphere FFM. 
Doing that can cause injury or death. 
Q: How can I check if my Besea W50 wing was one of the recalled wings? 
A: If you open the zipper on the outer wing bladder, and look at the inner bladder, you will find a small tab, that has some numbers stamped in to it. 
If you wing has the batch number 5445 stamped in to it, then you have a recalled wing. 
That batch, 5445, is the only batch that has been recalled. 
Q: What is the maximum size of the tanks i can use with the Besea? 
A: On the inside of the outer wing bladder, there is an inlay, that shows the maximum size tanks that can be used with the W50 and W100 wings. 
Q: How do I attach the Besea steel back plate to the harness? 
A: The Besea steel plate replaces the plastic plate that comes as standard with the Besea harness. 
Use the same bolts, nuts and holes to attach the steel plate. 
Q: Can I dive the Poseidon MKVI with Trimix? 
A: Yes. You need to upgrade the standard Poseidon MKVI with the 48M Deco Trimix battery or the 60M Hardware/firmware upgrade. You don't have buy the 60M Hardware/firmware upgrade at once you can start out as a recreational diver and as your knowledge progress you can upgrade your Poseidon MKVI. 
Q: Where can I see the serial number on my Poseidon MKVI? 
A: There are two ways of finding the serial number of your unit. 
- When you wet the two wet switches on the back of the display, the display will show the version number of the firmware installed and the serial number of the unit. 
- The serial number is engraved at the bottom of the e-module. 
We recommend that you write your serial number down and keep it in a safe place as you need it to perform value changes on your unit. 
Q: When I dive with my Poseidon MKVI, I get C1 warnings on my display. What is this? 
A: C1 is short for Confidence level 1, meaning that the primary oxygen sensor produces a response that is outside the allowed parameters, at a sensor validation. 
As the sensor gives a response not regarded as correct, the unit chooses not to trust the sensor, thus the alarm. 
This also includes the case if a sensor gives the exact same PO2 value at two consecutive validations. Then the unit thinks the primary sensor is frozen. If the PO2 value is changed at the next validation (approx. one and a half minutes later) the alarm will stop. 
All C1 alerts should be handled like a critical alarm and all instructions on the display should be followed. 
Q: When I do the pre dive test, I keep getting a 49 error. Why? 
A: An error on test 49 in the pre dive check indicates that the breathing loop is leaking. In most cases, it is due to the OPV on the exhalation lung not being closed or a damaged/missing o-ring somewhere in the loop. 
We recommend that prior to each dive, when putting your Poseidon MKVI together, all o-rings in the loop should be checked and lubricated. 
Q: My Poseidon MKVI will not pass the 53 test during the pre dive check. Why? 
A: Test 53 is the oxygen sensor validation test. If the pre dive test fails on this test, is because the primary oxygen sensor returns a value that is outside the allowed range, indicating a problem with the oxygen sensor. 
There are a few things you can do, to check if the sensors are bad or not: 
- Swap place between the primary & secondary sensor and run the pre dive again. 
- If it's cold, warm the sensors before doing the pre dive or do the pre dive indoors. 
- If you have put brand new sensors in to the unit, allow the new sensors to breath for 24 hours before you do a pre dive test with them. 
- Analyze the gas you use, to make sure the levels of oxygen are correct. 
If the unit continues to fail on test 53, replace one or both oxygen sensors. 
Q: The pre dive test keeps stopping on test 55. Why? 
A: Test 55 is the Service Interval test. When the Discovery is delivered, it has a service interval of 104 weeks. For each week that passes, this value is counted down towards 0. When the value is 0, the unit will not pass the Pre Dive check. 
To reset the service interval value, you need to take your Discovery to a Poseidon Service Center. 
Q: How deep can I dive with a Poseidon MKVI? 
A: The standard Poseidon MKVI is a recreational non-decompression dive rebreather with a max depth of 40 meters. 
This means that the unit will guide the diver to stay above 40 meters and not get into a decompression dive. 
Should the diver go deeper than 40 meters and/or go in to a deco dive, the unit will alert the diver by using light, sound and vibration alarm signals and it will also support the diver all the way to the surface, even if it requires decompression stops. It will also work at depth greater than 40 meters but it's not recommended. 
If you want to dive deeper or with decompression stops you have the following options: 
40M Deco Battery - Allows you to dive to 40M with decompression stops. 
48M Deco Trimix Battery - Allows you to dive to 48M with decompression stops and trimix in the diliuent. 
60; Hardware/Firmware Upgrade - Allows you to dive to 60M with decompression stops and trimix in the diluent. 
Q: Does my Xstream regulator have an over pressure valve in the first stage? 
A: The only Xstream regulators that has a built in over pressure valve, are those that has an article number that starts with 0100, complete regulator, or 0110, just a 1st stage. 
Q: There is a problem with my Poseidon gear. What do I do? 
A: The first thing you do, is to contact the dealer where you bought the item that’s causing the problem. Explain the problem to them and they will help you out if they can. 
If the dealer can’t fix the problem, they will in turn contact the local Distributor and if the Distributor can’t fix the problem they will contact Poseidon in Sweden. 
Keep in mind that you will be required to show proof of purchase and that it has to be a manufacturing- or material error to be covered by our warranty terms. 
Our warranty terms do not cover items sold used or problems that are related to normal wear & tear or improper handling of the equipment. 
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