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cylonboomer
January 26th, 2010, 05:53 PM
HEY GUYS!

I'm real close to deciding on regs, but I have a question on which first stage to buy.

Here's my situation...

I live in texas, and in the winter plan to dive from texas/oklahoma to florida. I think the coldest water will be around 45F. (I just got a dry suit) I'll be doing a lot of summer diving local, and hit the caribbean as much as i can.

So that's my story...now the real question. Would a first stage MK17 or MK25 be the better option?

Thanks for all your insights!

Boomer

Interceptor121
January 26th, 2010, 05:58 PM
For 45F I would recommend the MK17, however make sure you buy a decent balanced second stage (G250,S600,A700) otherwise is a waste
The Mk25 would have superior performance in cold water around 180 ft but maybe you don't go there anyway

cylonboomer
January 26th, 2010, 06:02 PM
Thanks for responding so quickly!...I plan on getting the A700 second stage. Would the MK25 freeze up at 45F? Those dives would probably be very few, but that would probably be the max. I think about 150F probably the lowest. Most of the cold water diving is around 50+....

So...Mk 17 or Mk 25 paired with an A700?

cbrich
January 26th, 2010, 06:21 PM
Where in Texas are you from? I have an MK25/A700 and dove in low 50*F water at 70'. I typically like to go deeper but I was diving wet and got cold. I know of folks that are diving MK25/S600 to 100'+ this time of year, and I have not heard of problems so far. I would talk to your local Scubapro dealer and ask them

I would recommend the MK25/A700, not because I have 2 of them, because they are great performing second stages. I also notice the air coming from the A700, is not as cold as the S600. I have been told that is because the second is metal not plastic, better thermoconductivity. The new S600 looks pretty good too.

rcs9250
January 26th, 2010, 06:37 PM
I dive the MK25/G250V in Lake Erie in the low 40's. I have MK17's on my deco cylinders. I'll be taking the MK25's beneath the ice in a couple weeks.
Take away any thermal considerations. I doubt you would notice any difference in the breathing. One consideration is if you dive in dirty water a diaphragm will be a bit wiser.

Pudsky
January 26th, 2010, 07:44 PM
Recently I just purchased new regs. I just got certified, and live in MN. I plan in the near future to start diving under the ice, and since lakes are cold here in MN pretty much all summer, I wanted a reg that I could use in warm water while on vacation and home in MN. I talked to people from several different shops and the overall opinion was to buy the MK 17. It has a balanced diaphram and is enviromentally sealed. I went with the G250V second stage, so far I love it. I would imagine the A700 would be similar to the G250V.

elan
January 26th, 2010, 07:52 PM
Thanks for responding so quickly!...I plan on getting the A700 second stage. Would the MK25 freeze up at 45F? Those dives would probably be very few, but that would probably be the max. I think about 150F probably the lowest. Most of the cold water diving is around 50+....

So...Mk 17 or Mk 25 paired with an A700?

I know some people even ice dive here with MK25 if tuned properly and using proper handling techniques I think you can still do it. Not that something I would recommend but I think for 45 MK25 should be ok . Though to be on the safe side I would go for 17.

rcs9250
January 26th, 2010, 08:02 PM
Here's my post from the other day on this board of a similar discussion. I put my MK25/G250V to somewhat of a test.

http://www.scubaboard.com/forums/regulators/318874-new-regulator-help-2.html#post4965421

halocline
January 26th, 2010, 09:07 PM
You'll be fine either way. 45 is not that cold for reg freezing. I don't know where you'll find water that cold in TX to be honest.

The other day I was diving in aquarena and a guy swam by with the A700 in his mouth on a miflex long hose with another A700 bungied on a necklace. I was sorely tempted to ask him to share air so I could check out the A700. I was breathing on a converted 109. Sort of old-meets-new.

Becca_007
January 26th, 2010, 09:26 PM
Most of my dives are done in Michigan and I went with the MK17/G250V setup. I have 8 dives in the 41-45F range, 9 at the 46-50F, 22 from 51-60F, 15 between 61-76F, and 14 at 77-80F. I've never experienced a free flow and am very happy with my choice.

cbrich
January 26th, 2010, 09:35 PM
You'll be fine either way. 45 is not that cold for reg freezing. I don't know where you'll find water that cold in TX to be honest.

The other day I was diving in aquarena and a guy swam by with the A700 in his mouth on a miflex long hose with another A700 bungied on a necklace. I was sorely tempted to ask him to share air so I could check out the A700. I was breathing on a converted 109. Sort of old-meets-new.

LOL, that was me you saw. I was helping out with the Diving for Science Class.

halocline
January 26th, 2010, 09:41 PM
LOL, that was me you saw. I was helping out with the Diving for Science Class.

Wow, how about that! It was in the training area right near the 'underpass' to cream of wheat. I was using double 72s, DM'ing for an OW cert class. Maybe we can meet up there sometime when we're both there and I can have a breath or two off the A700! They sure looked shiny.

This forum is really something...

cbrich
January 26th, 2010, 09:51 PM
Wow, how about that! It was in the training area right near the 'underpass' to cream of wheat. I was using double 72s, DM'ing for an OW cert class. Maybe we can meet up there sometime when we're both there and I can have a breath or two off the A700! They sure looked shiny.

This forum is really something...

LOL, I remember seeing you. You are second person I have seen with a set of doubles at Aquarena, first person had doubles & a deco bottle.

I try to go to Aquarena every other weekend or so. My regular dive buddy and I are planning to go out this Sunday, but depends on the weather.

Puffer Fish
January 26th, 2010, 09:55 PM
MK17 would get my vote...if you only have one regulator, make it the most flexable, sealed one you can.

That said, I have 2 Mk25/250V setups...but would not use them for really cold water diving.

Belce
January 27th, 2010, 12:17 AM
I use a Mk25 with an A700 up here and the water is a little colder than you plan on and the air temp at surface can be even below freezing and have never had an issue with freezing. The Mk17 is a great 1st stage as well and your choice, but I see way more mk25 up here than Mk17's and have never seen or heard of trouble with them.

divin'dog
January 27th, 2010, 12:21 AM
I have the MK17/A700. Got the MK17 based on what DA Aquamaster had written on this board comparing the 17 and 25... So far, I love the MK17/A700.

This is only one link... there are others.
http://www.scubaboard.com/forums/regulators/312359-mk25-superior-mk17.html

Interceptor121
January 27th, 2010, 05:16 AM
MK17/A700 is a fabulous choice if you have the budget I don't see any better options

DA Aquamaster
January 27th, 2010, 08:19 AM
As noted in previous posts, I switched from Mk 25s to Mk 17s soon after the Mk 17 was released. At the time I was diving exclusively in coldwater with bottom temps in the 35-39 degree range at depths to 150'. While I personally never had a freeze flow, I was with divers using the Mk 25 S600 who did. The difference may have been in technique, it may have been the difference in second stages (I used D400s and for a short while X650s), or it may have ben a combination of both.

In any event I switched as the Mk 17 is much more reliable in cold water and does not depend on perfect codl water technique to acheive it while the Mk 25 demands it at temps much below about 45 degrees, especially with the S600 due to the S600s poor heat transfer traits and a tendency for it do develop a very slight freeflow that in turn increases the heat transfer demands on the Mk 25.

I don't agree with the statement above that the Mk 25 would be a better cold water reg at 180'. I am assuming that statement is based on the Mk 25 being certified by somebody for cold water use at that depth. That would just confirm the Mk 25 meets some minimum at that depth, but does not change the fact that the Mk 17 is more reliable in cold water. This is especially true at greater depths where higher flow rates greatly increase the heat transfer demands placed on the Mk 25.

In terms of flow rate the Mk 25 will flow about 300 SCFM while the Mk 17 "only" does about 220 SCFM, but then even the highest performance second stage available only flows about 70 SCFM, so the Mk 17 has more than enough flow rate to support 3 second stages at maximum flow rates.

I also put very little value in the "most people I see use the Mk 25" argument as it is nothing more than an ad populum logical fallacy. Scubapro pushes the Mk 25 as its premier reg in the US and many Scubapro dealers and customers have 40 years of history with the basic Mk 1/5/6/8/9/10/15/20/25 piston design and are not inclined to adopt any diaphragm reg - even one that is superior in most respects to the Mk 25 and gives up nothing of value in terms of real world performance. That resistance to change has nothing to do with the actual capability of the Mk 17.

cylonboomer
January 28th, 2010, 06:19 PM
Thanks everyone for their experiences. I'm still on the fence, but have a lot to think about. One question though, and this is probably a stupid one, but does a yoke vs Dinn fitting make a difference on how the reg handles temperatures?

halocline
January 28th, 2010, 07:32 PM
Thanks everyone for their experiences. I'm still on the fence, but have a lot to think about. One question though, and this is probably a stupid one, but does a yoke vs Dinn fitting make a difference on how the reg handles temperatures?

Nope. Well, there is one sort of very stretched condition; DIN fittings are usually associated with higher pressures, and a reg operating under higher pressure is theoretically more likely to freeze.

So, if you're concerned about your reg freezing in 45F water (which you should not be) use lower pressure tanks. I'm still wondering where you'll find water that cold in TX. Let me know, so I can make sure to avoid it!;)

cylonboomer
January 29th, 2010, 10:28 AM
Mattboy
I hope I don't find lakes that cold. But since I now have a dry suit, I am wondering if i should consider buying a reg that "can" go that cold. I hate being shortsighted when buying gear....
What are the cold temps of water in winter in texas??

lxchin
January 29th, 2010, 01:20 PM
mk17 is envoronmentally sealed. so will give the the extra assurance of not freezing up. also will be a bit cheaper than the mk25's.

cylonboomer
March 9th, 2010, 04:46 PM
Well I ended up w/ a MK25 DIN/A700 :D..oh and a Luna.
Happy with it all! Thanks for all the input everyone!!!

ScubaAJ
April 20th, 2010, 08:13 AM
I have the MK17/A700. Got the MK17 based on what DA Aquamaster had written on this board comparing the 17 and 25... So far, I love the MK17/A700.

This is only one link... there are others.
http://www.scubaboard.com/forums/regulators/312359-mk25-superior-mk17.html

Wow thanks! I am definitly going for the Mk17/A700 after what I just read. You just saved me alot of money :D


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