drasher502
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is there a noticeable breathing difference between the two or is it something that you really can't tell any difference? i am getting ready to buy one of the two.
scubapro mk17 s555 vs. mk25 s600
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Pearldiver07
Contributor
I used to sell both of these at the shop I managed.
I truly believe that you're not going to be able to tell the difference in terms of breathing.
What you will find is that the port arrangements are different and the s600 second stage has an adjustable cracking pressure. I personally believe that this feature is over rated for most people. Unless you swim into currents, work on the surface a lot and want to de-tune the reg (as in teaching) so it doesn't free flow, or some other situation like this, you won't have much reason to have an adjustable cracking pressure.
But I will say that the port arrangement on the first stage will make a difference. Please look at your rig and try to discern what layout will make more sense. I went with the Mk25 because of the layout. Because I dive everything from light recreation to tech diving I thought the options presented were better. Your mileage may vary, of course.
Bottom line? IMHO you can't really go wrong between these two regs. You'll enjoy which ever one you decide on.
Good luck and enjoy!
I truly believe that you're not going to be able to tell the difference in terms of breathing.
What you will find is that the port arrangements are different and the s600 second stage has an adjustable cracking pressure. I personally believe that this feature is over rated for most people. Unless you swim into currents, work on the surface a lot and want to de-tune the reg (as in teaching) so it doesn't free flow, or some other situation like this, you won't have much reason to have an adjustable cracking pressure.
But I will say that the port arrangement on the first stage will make a difference. Please look at your rig and try to discern what layout will make more sense. I went with the Mk25 because of the layout. Because I dive everything from light recreation to tech diving I thought the options presented were better. Your mileage may vary, of course.
Bottom line? IMHO you can't really go wrong between these two regs. You'll enjoy which ever one you decide on.
Good luck and enjoy!
A few years ago I switched from Mk 25's on my doubles to Mk 17's as they offerred better codl water performance. During the transition I put one of each on each post with the same top of the line balanced second stages on each post and could not tell one from the other. I even tried it with the regs feeding the same second stage through a gas block at depths to 150' and there was no difference even in a blind test where I did not know which stage was deeing the reg at a given time.
So in effect, the Mk 25 has a lot more flow rate (300 SCFM compared to 175 SCFM for the Mk 17)but the Mk 17's flow rate is well above the 140 SCFM needed for even the most demanding deep/techncial dives and about 2.5 times the flow rate of the best second stages availble.
So the Mk 25 is overkill and in my opinion it comes at the cost of cold water reliability as it is prone to freeze flows in water colder than about 45 degrees.
On double tanks I prefer the MK 17's hose routing. However on a single tank with a long hose primary, I prefer the Mk 25's hose routing as when you put more than 2 LP hoses on a single Mk 17, you have to mount it so that the hoses go out sideways rather than straight down. With the Mk 25, you can route the long hose out the end port and cant the reg at about a 45 degree angle, leaving the HP and the other 2 LP ports angled down at a 45 degree angle creating fairly clean hose routing.
On a single tank with a short hose primary, it is a wash with either first stage.
Both are great regs with the cold water edge going to the Mk 17. Plus the fully sealed Mk 17 does not require the ambient chamber to be rinsed, a slight advantage even in warm water diving. The Mk 17 is also lighter and more compact and is more travel friendly.
I agree the adjustment on the S600 is not a big deal and other than the adjustment knob the S555 and S600 are identical. That said I am not an S600 fan. It is smaller and "lighter" than the larger G250HP and G250V, but the latter have both a larger diaphragm to power the same internal parts and they have more buoyancy in the water meaning the extra weight is a wash in the water and is not a factor at all in jaw fatigue. Smaller is not really better in a regulator.
The G250V also has a metal air barrel that reduces dry mouth and improves heat transfer and cold water performance so it is a much more flexible and capable second stage than the S600.
Consequently, my choice would be a Mk 17 G250V.
So in effect, the Mk 25 has a lot more flow rate (300 SCFM compared to 175 SCFM for the Mk 17)but the Mk 17's flow rate is well above the 140 SCFM needed for even the most demanding deep/techncial dives and about 2.5 times the flow rate of the best second stages availble.
So the Mk 25 is overkill and in my opinion it comes at the cost of cold water reliability as it is prone to freeze flows in water colder than about 45 degrees.
On double tanks I prefer the MK 17's hose routing. However on a single tank with a long hose primary, I prefer the Mk 25's hose routing as when you put more than 2 LP hoses on a single Mk 17, you have to mount it so that the hoses go out sideways rather than straight down. With the Mk 25, you can route the long hose out the end port and cant the reg at about a 45 degree angle, leaving the HP and the other 2 LP ports angled down at a 45 degree angle creating fairly clean hose routing.
On a single tank with a short hose primary, it is a wash with either first stage.
Both are great regs with the cold water edge going to the Mk 17. Plus the fully sealed Mk 17 does not require the ambient chamber to be rinsed, a slight advantage even in warm water diving. The Mk 17 is also lighter and more compact and is more travel friendly.
I agree the adjustment on the S600 is not a big deal and other than the adjustment knob the S555 and S600 are identical. That said I am not an S600 fan. It is smaller and "lighter" than the larger G250HP and G250V, but the latter have both a larger diaphragm to power the same internal parts and they have more buoyancy in the water meaning the extra weight is a wash in the water and is not a factor at all in jaw fatigue. Smaller is not really better in a regulator.
The G250V also has a metal air barrel that reduces dry mouth and improves heat transfer and cold water performance so it is a much more flexible and capable second stage than the S600.
Consequently, my choice would be a Mk 17 G250V.
OP
drasher502
Registered
thanks guys i appreciated the comments i will go with mk17 s555
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