Scubapro MK25 First stage for a dive to 200 ft?

[DandyDon]

Man, I never come into this forum, as I certainly don't know enough to add anything, but now - even after a Search - I have a question:

In talking with the LDS & Tech I trust to service my Regs {even know his wife and kid, etc.}, I told him I might pursue some Tech courses, i.e. Decom Theory, Advanced Nitrox, and that we might do a 200 foot dive together.

He confirmed my choice in an Instructor, and suggested I upgrade to this First Stage. Says I can use my old Second states, and make the move for about $100 more than just servicing my 3 year old CDX Oceanic. The price is certainly right.

I do want to stick with his brands, as he's the only Tech I know and trust nearby. But would you have anything bad to say about this model to 200 feet?

thanks!

 

[matt_unique]

Man, I never come into this forum, as I certainly don't know enough to add anything, but now - even after a Search - I have a question:

In talking with the LDS & Tech I trust to service my Regs {even know his wife and kid, etc.}, I told him I might pursue some Tech courses, i.e. Decom Theory, Advanced Nitrox, and that we might do a 200 foot dive together.

He confirmed my choice in an Instructor, and suggested I upgrade to this First Stage. Says I can use my old Second states, and make the move for about $100 more than just servicing my 3 year old CDX Oceanic. The price is certainly right.

I do want to stick with his brands, as he's the only Tech I know and trust nearby. But would you have anything bad to say about this model to 200 feet?

thanks!

Short of the hit or miss experience people have had with freezing in colder temps, the MK25 would be one of, if not the very best reg for breathing in the deep.

--Matt

 

[Doc Intrepid]

I would agree with Matt.

I have the Mk-20s, older than the 25s. They are excellent regulators. I have taken them to 200'. As an aside, some of my buddies own Apeks regs. During OOA drills they expressed surprise at how easier my regs were breathing than theirs. SP makes some extremely good regs, not that I'm dissing anyone elses.

I will tell you that choice of regs for deeper dives can be important. I also own a set of Sherwood Magnum Blizzards I bought for cold water diving. I had one on an 80, slung. I did a gas switch to the 80 at 120' off the Scubapros. Comparatively it felt like I was sucking through a small tube - a huge difference. At first I thought something was wrong. It was an extremely uncomfortable sensation. FWIW, I recommend you listen to your tech.

 

[Scubakevdm]

Mk25 is the one. If you haven't made up your mind before the trip you can try mine. FWIW I'm also a tech, it's what I dive. I wonder what DA Aquamaster dives.... he lives where it's cold I think.

 

[drbill]

Hmmm... I've taken my Mk10 G250's to 150 ft. What do more knowledgeable deep divers think about that config for depths up to 200 ft.

Doc

 

[DA Aquamaster]

I dove Mk 25 D400's for about 130 dives last year and had zero problems at depths to about 150 ft and in water temps below the thermocline of 39-44 degrees. And this was with older MK 25's without the heat transfer fins on the cap. But I also used LP steel tanks and I think that can make a difference.

A frequent buddy of mine froze up with me on 4 of the same dives with a new Mk 25 AF S600 and high pressure tanks. (He got very good at closing valves by the end of the season.) I think the Mk 25's flow rate can push the TIS system to the limit in water colder than about 45 degrees with the increased adibatic cooling that occurs with high pessure tanks.

This year I went back to using MK 20 D400's with the late production SPEC boots and filled ambient chambers. It's not that I ever had a problem, I just got tired of worrying about having one. The SPEC booted Mk 20 will sustain a continuous freeflow in 32 degree water without freezing and that sort of cold water reliability inspires confidence.

That said however, I have no reservations using a regular TIS equipped MK 25 in water warmer than 45 degrees and a Mk 15, 20 or 25 with a decent second stage is very hard to beat for air delivery at depth.

I also think the S600 is perhaps bit more likely to freeflow slightly and provoke a freeze-flow in very cold water with a MK 25 than a G250 or the older and even better (and unfortunately discontinued) D400.

Harder breathing regs in my opinion are not a good idea at depth as they increase air consumption and also create an increased potential for CO2 buildup which can start a chain of events that you are far better off avoiding. Most diaphragm regs are hard pressed to compete with a Mk 25 at extreme depths.

 

[Scubakevdm]

I also think the S600 is perhaps bit more likely to freeflow slightly and provoke a freeze-flow in very cold water with a MK 25 than a G250 or the older and even better (and unfortunately discontinued) D400.

Hmm... you don't like the X650?

 

[DA Aquamaster]

I have not tried the X650 yet. In looking at it, it appears to have the same advantage in case geometry as the D400 but also seems to have missed the marka bit by not retaining the D400's co-axial diaphragm and exhaust valve. Still, it should potentially be better than the S600.

I know a lot of techs did not like working on the D400 as it was a bit different and with the newer plastic orifice getting it fined tuned was a little tougher. But it was an excellent breathing reg both from a numbers standpoint and in terms of a natural feel.

 

[Scubakevdm]

It(the X650) is perhaps the best breathing second stage I've ever used, definately easier breathing than the s600 that I own. I am told that the changes were made (to the D400)in an effort to make it a bit less tempermental. Sources close to me indicate that they were effective, though as you point out some amount of performance was sacrificed to that end. In any event ScubaPro can't make them fast enough now.

 

[Hank49]

thanks![/i]

I've dived on air to ppO2 1.7 at least 60-70 times with an MK20 and Atomic B1. Also used G250 with same first stage. No problems at all.