Scubapro S555 versus S600

[redacted]

What I do not like of the S600 is divers that play with the adjustment knob believing that they would use less air if they make it harder to breath but that is another story

Agreed. That is a misconception some divers have. The easier a regulator breaths, without freeflowing, the less work a diver has to do to breath. Reducing work load reduces consumption. Admittedly, after some point, the difference are so small as not to be noticeable and higher performance at that point may not be worth higher costs if you can not benefit from it.

 

[Hank49]

I have a 555. I got it after using an Atomic B1 second for a few years and also G250s. I like the simplicity and I can't tell any difference in breathing between all of them.

 

[Interceptor121]

Going back to the original question I would recommend the S555 unless you dive in very diverse conditions that may benefit the fact that you have an adjustment knob

 

[scubajo007]

Thanks for the answers,

My first stage is MK11. To be honnest I dont much about it, I'm still at the bottom of the learning curve so can any of you explain in simple terms in which conditions and when the S600 would be beneficial.

Cheers
Scubajo007

 

[Interceptor121]

Let's put it simple. If you always dive in similar conditions the S555 is fine
If you do mix of warm and cold water maybe the S600 is a better choice

 

[JoshP]

I dive a Mk11/S555 as my primary, and have not run into any problems with it. I mostly do rec diving (30'-60') off the Cali coast.

 

[darkarchangel]

I own both the mk17/s555 combo and a mk25/s600 combo. I am in the navy so i travel a lot and end up in all kind of locations around the world. I use my s600/mk25 when i am diving some of the springs here in florida. i use my s555/mk17 when i am diving back home in the caribean or tropical places. both are good 2nd stages but at the end it comes down to personal preference. if you want a reg that you dont want to have to upgrade for a while i say go for the s600.

 

[halocline]

Thanks for the answers,

My first stage is MK11. To be honnest I dont much about it, I'm still at the bottom of the learning curve so can any of you explain in simple terms in which conditions and when the S600 would be beneficial.

Cheers
Scubajo007

The MK11 is (I think) the newer version of the MK16, which means it's a perfectly acceptable non-sealed diaphragm reg, very similar to the MK17 without the environmental seal, which by the way you would only need in extremely cold water. So, your first stage is fine at any recreational depth, and way beyond if you head in the tech direction.

Most people seem to forget that decent quality modern 1st stages can typically flow quite a bit more than 100SCFM, which is the equivalent of draining an AL80 in about 40 seconds. The tank valve flows slower than a good first stage, and ALL 2nd stages flow much less, often less than half, of the flow rates for 1st stages.

The conditions that would favor the S600 over the S555 are things like very high current where you might want to stiffen the breathing to help prevent a freeflow from the current pushing on the diaphragm. Another 'condition' might be if your reg is getting close to needing service and there's a slight freeflow from the seat wearing, you could simply tighten the adjustment. But, in the case of these regs, there's a seat saver which releases most of the pressure on the seat while the reg is not attached to a tank, and there's a plastic orifice which quite honestly does not perform as well as the older metal ones, but also probably does not wear the seat as much.

It's up to you, either one is fine. As I mentioned before, you'd probably notice more of a difference with the G250V.

Or you could do the right thing, forget this new 2nd stage bit, and get a D400. You'll spend less and get a better reg, but that's just my totally subjective opinion.

 

[tarekaly]

I just to make sure of one point.

Divers benefit of the ease of breathing adj knob in which conditions more? during deep dives or when they are tired?
I have a new G250 and want to know when to better utilize this knob

 

[redacted]

I just to make sure of one point.

Divers benefit of the ease of breathing adj knob in which conditions more? during deep dives or when they are tired?
I have a new G250 and want to know when to better utilize this knob

Normally, you want to keep that knob in the easiest breathing position while diving. A couple exception are during a surf entry or exit and in currents where those conditions might cause a freeflow. Also, if it is tuned for maximum performance and, after the LP seat takes a bit of a set, you encounter a slight leak; you can detune it slightly. Also, If you happen to be using that reg as an octo, you should use that control to detune it until you have to use it.