MK16/S550 or MK25/S600?

[Fernando]

Hi, everyone. I'll be shopping for a regulator soon and I can't decide between this two. The appeal of the S600 for me is the possibility to adjust the air flow, allowing myself to push back the air consumption, but still being able to get as much air as needed in rougher situations. The MK16/S550 combo, in the other hand, is lighter in weight and in the wallet. Also, if I choose to go the Mk25/S600 way, is it worth getting the MK25AF/S600T instead, for $25 more?

I plan to take a deep diver specialty in the next couple months. I also plan to get tech diving certifications, say, three years from now. I dive warm waters all the time (60ºF and up).

Which would you choose?

Thank you and dive safe,
Fernando

 

[KMD]

Hi, everyone. I'll be shopping for a regulator soon and I can't decide between this two. The appeal of the S600 for me is the possibility to adjust the air flow, allowing myself to push back the air consumption, but still being able to get as much air as needed in rougher situations. The MK16/S550 combo, in the other hand, is lighter in weight and in the wallet. Also, if I choose to go the Mk25/S600 way, is it worth getting the MK25AF/S600T instead, for $25 more?

One would never EVER want to detune a reg to adjust for air consumption. This could lead to hypercarpnia (Co2 buildup) and hypoxia (insuffecient Oxygen) both very very serious conditions underwater.

The venturi lever and the free flow knob have nothing to do with air consumption. They simply control how easy the regs breathe. The advantage to having the adjustment knob is that if regs get slightly out of tune and start free flowing you can "de-tune" them on the spot by increasing the cracking pressure.

For both of my S600's I have had tuned to a high performance. My backup is venturi lever is set to predive and the primary is set to dive. While I sometimes have to fiddle with them a bit to stop the slight freeflow during a reg switch, I would much rather deal with that then risk going to the backup and having the feeling of sucking my gas through a straw.

 

[Jason Ooi]

I used MK25/S600 and MK17/S600 for tech dive good performance regs never regret

 

[Vie]

Hi, everyone. I'll be shopping for a regulator soon and I can't decide between this two. The appeal of the S600 for me is the possibility to adjust the air flow, allowing myself to push back the air consumption, but still being able to get as much air as needed in rougher situations. The MK16/S550 combo, in the other hand, is lighter in weight and in the wallet. Also, if I choose to go the Mk25/S600 way, is it worth getting the MK25AF/S600T instead, for $25 more?

I plan to take a deep diver specialty in the next couple months. I also plan to get tech diving certifications, say, three years from now. I dive warm waters all the time (60ºF and up).

Which would you choose?

Imho, go with the MK17/G250HP or MK25/G250HP. If you plan to dive warm water only, then the MK25 is excellent and offers great hose routing options for AL80 singles/doubles (compared to the MK16/17). If you really must have a small second stage then the MK25/S600 is great - I don't think you can get a MK17/S600 combo yet but the MK17/S555 is also a possibility. Avoid the (imho) completely pointless titanium MK25T/S600T and the "lightweight" MK25SA.

 

[Fernando]

thanks, everyone, for your inputs, especially KMD, for the explanation about the flow adjustment. It makes total sense.

Why is the MK25 only suitable for warm waters? And what about the MK25AF?

Thanks again,

Fernando

 

[Vie]

Why is the MK25 only suitable for warm waters?

It's a fine reg in most conditions but it does have somewhat of a bad reputation in extremely cold water, especially when paired with the S600 second stage.

 

[mart1]

MK25 S555 perfect combination also for cold water

 

[halocline]

You should probably be aware that when they say "cold" water, they're talking about water less than 40o F. That's REALLY cold. I'd second the G250 recommendation; SP is about to discontinue it and it will be harder to find. If you want to save some money, see if you can get a MK16/G250 combo at a discount, because the MK16 is also discontinued and as such, the dealer is allowed to sell it for quite a bit less than retail.

 

[Hoosier]

Get MK25/S600 for the warm water. You need to think about the resale value and market if you don't plan to keep it forever. I have MK25AF/S600 and MK25AF/G250HP, but MK25AF/S600 is much easier to sell later....

 

[DA Aquamaster]

If/when Scubapro discontinues the G250HP dealers will be able to sell them without complying with the existing pricing guidlines requiring them to sell them for no less than 10% under MSRP. That means dealers could sell them for a little over their cost which is usually a little more than 1/2 the MSRP. Plus the regs are still sold with full warranty so if ypu have a marketing savvy dealer who takes advantage of this, you will be able to get Leisure Pro pricing and also get full SP warranty and support.

If SP discontinues the G250HP it will also be a very sad day as it is a superior performing regulator that has proven to be very reliable in cold water. The S600 is identical to the G250 except it has a smaller case and it has a tendency to freeflow slightly in very cold water.

The Mk 25 is a good reg in water warmer than 50 degrees F, but in water colder than about 45 degrees F it has been known to ice up resulting in a violent freeflow.

The Mk 17 is virtually bullet proof and is a very reliable diaphragm design. Parts count differs little from the generic balanced diaphragm reg design. It does however have a separate air passage to the balance chamber (a good thing) and this requires one additional o-ring. It also uses a separate seat and seat guide rather than the one piece unit used in most other designs, but it is a superior design and the extra part is not going to cause any reliability problems.

It also incorporates a diaphragm sealed dry ambient chamber which is very low maintence and very effective at keeping dirt, salt, etc out and provides excellent reliability in very cold water. It is, in my opinion, the best cold water first stage you can currently get.

In my opinion a Mk 17 G250 would be an ideal reg. It is not packaged that way, but your dealer can order it that way from Scubapro. Similarly, you can also order the MK 17 S600 the same way. You lose a few percentage points with the loss of tyhe package discount, but you more than get those savings back from paying a little (S600) or a lot (G250HP) less than you would for the X650 the Mk 17 is normally packaged with. A special order like that only takes a week to 10 days to get from Scubapro.

With regard to resale value, I'll argue the G250HP will have a higher resale value if it is discontinued and once remaining stocks are liquidated as they will no longer be available and those who want them will pay much more for them on the used market. In contrast if you are selling a still in production S600 second stage, you will be competing with Leisure-Pro selling new discount priced non SP warrantied S600's which will effectively set a price cap for your used non SP warrantied S600. Believe me, under those conditions you will get more money for a used G250HP than you will for a used S600 as the G250HP has a very loyal following.

SP also has a long history of supporting regulators long after they are discontiunued (as in for decades after they are discontinued) so being discontinued does not mean the useful life of the reg will be shortened in anyway.