scubapro 600s/mk25 cold water performance

[pgilman1]

Process of buying 1st and 2nd stage for summer diving in North Atlantic and the finger lakes. How does the 600s/MK25 perform compared to the other manufacturers?

 

[buddhasummer]

I have no idea of the water temps there at that time but the Mk25 is not recommended for temperatures below 50f/10c. From 2011 I believe the S600 air barrel was replaced with a metal one so I imagine would be fine for cold water use. I know some people use the MK25 in cold water without issue but for colder water you would be better off with a sealed 1st stage. SP MK17 would be more suitable. One of the scubaboard reg gurus rates the MK17 1st stage very highly, his opinion is to be trusted. Hopefully he or others more knowledgeable than I will chime in.

The MK25 is SP flagship 1st stage and prior to the A700 the S600 was their flagship 2nd stage. They are all very high performance regs.

 

[Bottom Surveyor]

What buddhasummer said.
Furthermore, MK17/G250 (or the newer G260) might be an even better cold water combo.
Alternatively, have a look at Apeks regs, they have excellent reputation as cold water regs.

 

[novasquid]

I have no idea of the water temps there at that time but the Mk25 is not recommended for temperatures below 50f/10c.

Interesting, the scubapro website says the MK25 is good down to 36F. i'll never dive in anything below 45F so it's a moot point to me, but thought i'd point that out.

 

[buddhasummer]

Interesting, the scubapro website says the MK25 is good down to 36F. i'll never dive in anything below 45F so it's a moot point to me, but thought i'd point that out.

Is that when they are packed with grease?

 

[halocline]

The MK25 has a checkered reputation in cold water. It is used frequently in cold water without problem; that seems to be somewhat 2nd stage dependent. But you do hear about freezing problems with the smaller plastic 2nd stages. I suspect that it's okay down to low 40s, but that's more-or-less a guess on my part. It's not an ideal choice for cold water, and there are others, so it doesn't make sense to choose it.

It is a fantastic 1st stage though, so if you're getting a deal and your expected temps are in the 50s maybe dipping into high 40s, probably fine.

---------- Post added June 5th, 2013 at 07:27 AM ----------

Is that when they are packed with grease?

Too bad SP discontinued the SPEC system that worked so well on the earlier balanced piston regs in favor of the service-tech-friendly TIS system of bushings and sleeves. So unfortunately you can't easily pack a MK25 like you can the MK5/10/15. The big oval ambient chamber holes will really allow grease out and water in. That's one thing atomic got right; they went back to the optional environmental grease with a boot to keep it in place.

 

[eelnoraa]

I have no idea of the water temps there at that time but the Mk25 is not recommended for temperatures below 50f/10c.

Is that when they are packed with grease?

I think 50F/10C is very conservative for Mk25. In fact, for any regulator at all, cold water or not. I have used it in 45F many many times, it is far from having freezing issue. I don't know what the temperature I should start concerning. My guess is below 40F

As far as I know, Mk25 can't be packed with grease

 

[Mikko Ilari Laakkonen]

Just dove a brand new mk25/g260 set a few times under the ice for a few times last winter. Surface temperature -10 at worst and water +1c. No freeflow or freezing problems at all and amazing performance.

 

[elan]

I dove a bunch of piston stages this winter in lake ontario with water temp between 36 and 39. those were Mk20,25,15,5
I always had a good cold second stage attached to them, A700,BA156, G250 S600(metal barrel) and a converted Pilot. None of them free flowed ever.
the problems with those 1 st stages start when you overcool them on the surface. So if the surface temp is below freezing and you have to keep the rig outside before or between the dives you will run in to a problem. Or if you have a finiky second stage like old S600 G250HP they usually start flowing first later taking down the first stage. I also only dive LP tanks so that helps a lot.

 

[CPH]

I have seven sets of Mk25's with various seconds. GV250s, S555s, R395s and A700s.
In the winter we regulary do ice dives and have never had a free flow.
Just remember NOT to breath the reg while it is out of the water.