Neptune Space w/ScubaPro First Stages

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ddball

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Scuba Instructor
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Location
NE Indiana
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Thanks in advance for any information you can provide.

I am a Volunteer Firefighter/Medic and the Water Rescue Captain of our local Fire Department. We recently received a very healthy grant from our Local Government which allowed us to purchase a great deal of equipment for our Water Rescue Team, including full face masks for our Divers. I am a PADI Master Scuba Diver Trainer and am working on my IDC Staff Instructor certification.

Well, this past weekend, I braved the 43 degree water of France Park in Logansport, Indiana, to complete my Full Face Mask Instructor certification. Chalk up another (Distinctive) Specialty that I can teach!! I must say, it was more of a struggle than I originally expected.

The mask we purchased for the team is the Ocean Reef Neptune Space unit, with the built in second stage and diver to diver/diver surface communications unit. This mask seems to fit our needs, with the quick connect hose and swivel, and the relatively inexpensive price tag.

While in the pool two weekends ago, I found the mask fairly easy to don and adjust. The breathing was made easier by the built in adjustment knob, but seemed very touchy to balance between "too hard" to breathe and a free-flow condition. In the pool, I had the Space mask mounted to a ScubaPro MK25 first stage and was able to pass all the required skills easily.

This past weekend, I changed over to my ScubaPro MK17 first stage for the cold water dive. I've found the MK17 to be a bit better in cold water, at least, using the tried-and-true G250 second stage I have come to trust. However, this time, the mask seemed to breath much heavier than in the pool, which I initially attributed to the cold water. But the balance on the adjustment knob was almost impossible to hit. I was either free-flowing or really pulling on the second stage to get a breath.

Wearing a hood made the mask difficult to seal to my and the dry gloves made it difficult to make adjustments on the mask, especially during the mask removal and replacement. The constant "tinkering" with the adjustment knob to stop a free-flow really made enjoying the dive difficult. It was also nearly impossible to breathe from through my nose, the cracking pressure required to supply the air seemed too high.

Now, we can't always determine the conditions under which we dive. We need to be sure of the mask's capabilities and, as a dive team, trust it to provide adequate service in any conditions, including cold water. I can't always dive in 80 degree water with no hood or gloves!!

Should I look into purchasing the Neptune first stage instead of using the ScubaPro models? Should I have the second stage checked to see that it is working correctly, perhaps balanced with my MK17 or MK25? Our department regulators are all ScubaPro, but not all are MK17s or MK25s. Are there some that will not work with the Neptune Space?

Any information you can provide would help greatly.

Dave
 
Welcome to the board Dave.
The bottom line is, the second stage could care less what the first stage is. As long as the first stage is delivering air with a sufficient flow rate and a stable IP (pressure of the air in the hose) then the second stage will perform fine. The specs on both those regs (and 90% of all the rest of the first stages on the market today) are close to the same and assuming they are both performing anywhere close to factory specs it would be impossible for the user to tell the difference between them. Either one of your first stages is not up to snuff or there is something else going on but it has nothing to do with the MK-25 vs MK-17.
If I were looking for the problem, I would be looking hard at the mask's second stage, esp since it's new.
 
I'm using the Ocean Reef Neptune with a ScubaPro Mk10+ first stage. Never had any problems with the setup.
Were you mostly having problems in shallow water? We've found that under about 10 feet they can be a bit finicky. We just set them to breathe a little hard at shallow depths and then just readjust when deeper. If working in real shallow water (like 5 feet), and you are looking straight down, sometimes it helps to turn the exhalation valve to the off position. Air will still blow out the seals on your face, but it will be more difficult for the reg to free flow.

We've also found that trimming back the face opening on a standard drysuit hood helps with Neptune/hood issues. Put on hood. Put mask on over hood. Use a piece of chalk to trace around mask onto hood. Take off mask/hood (duh!). Cut hood along chalk line.
Don't try to seal the mask to your face with neoprene in between mask and hood. The seal will be crappy, and you'll never get the nose pieces to hit your nose. Trim the hood so that the mask can seal to skin.

I'd check the ScubaPro first stages Intermediate Pressure (IP). The ScubaPro's have a track record of IP creep when not serviced properly or old/worn. I'd think that this would increase the cracking pressure, and cause other problems.

The Neptune Space Mask owner's manual states; "1st stage intermediate pressure not 140 +-3psi / 9.5-9.8 bar" as a reason for the problems "Free-flows" "Hard to Breathe" and "FFM Vibrates".

The MK20/25 IP (per the service manual) should be set between 125-145 psi.
 
https://www.shearwater.com/products/swift/

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