Scubapro G250HP and S600 2nd stages

[DA Aquamaster]

I've been diving on a mk25/s600 setup for some time now. I absolutely love it. Personally I think the s600 breaths better than the 250 or 190's. My air consumption rate also improved with it over my 190. The one thing I have noticed is that if you are ice diving with it, the smaller regs tend to freeze up a little more than the bigger regulators (like the 250 or 190).

I think the materials used in the construction of the second stage has more to do with it than the size of the second stage.

The S600 has a plastic air barrel in it that allows very little heat transfer so the potential for ice formation is higher than on a G250 with a metal air barrel and the S600 is much more likely to freeze than an all brass second stage like a Balanced Adjustable.

In terms of breathing performance, it is highly questionable to use "G250" and "R190" in the same sentence even though the case sizes are similar.

The G250 uses a balanced poppet while the R190 uses a standard downsrteam poppet design. While an R190 can be made to breathe exceptionally well if it is on a balanced first stage, it lacks the adjustment knob of the G250, and cnsequently R190's tend to come back in to the shop a lot due to minor freeflows if set up with a minimum cracking effort. Consequently many shops detune them a bit to prevent the customer from getting angry at having to come back in to have the orifice tightened a smidge after a seating groove develops in the second stage seat.

 

[diverUp]

What do you guys think about these two 2nd stages. They are almost the exact same save for the S600 is much smaller. Is the size issue worth the extra money?

I have the S600, 250 and G250HP, I like them all but by far my favorite is the G250HP. I cant tell the difference in breathing between the 600 and G250...BUT when I dive in temperatures below 40 degrees my 600 will free-flow, while my G250 performs flawless!

IMO, save the cash and go for a G250HP

 

[DA Aquamaster]

Our SP tech rep has made essentially the same comment about the S600 being freeflow prone. To SP's detriment the MK 25 / S600 combo is pushed very hard and in the end the S600 just aggravates and precipitates the freeflow problems the MK 25 can have in cold water.

The only advantage the S600 offers is a smaller case. It offers no performance advantage whatsoever over a G250HP and as pointed out above, the G250 is a far better choice for cold water diving.

 

[bjpell]

is the purge button on the 250 just the blue logo in the middle? or is it the whole front? Looks as though the s600 is the whole face.....

 

[ElectricZombie]

I have an S600, a G250HP and an old G250. They all breath about the same to me. I could care less about the size of the 2nd stage. I like the idea of a larger diaphram anyway. If you want to save some cash, go with the G250HP.

 

[MCL]

I have the G250HP and it is great. I have no complaints.

 

[sylvester]

I have a mk25af and s600 primary and older g250 octo. I like both, when I first got my setup the mk25 was the original and it free flowed a few times in cold water when I was stationed in Missouri. Now I live in Pa the water is colder for more of the year I had my reg upgraded with the AF kit, and detuned so my IP is 130, I have dove some much colder water here then in Mo this past winter with out a few flow or any other problem, I can not tell the differance between an IP of 130 and 145. Maybe you can, but I am pleased with my setup as is. My wife and I have used my primary and Octo simutaiously to see if we could over breathe the mk25 with the lower IP and we had no problems with it.

My $.02, you'll be happy with either.

 

[DA Aquamaster]

is the purge button on the 250 just the blue logo in the middle? or is it the whole front? Looks as though the s600 is the whole face.....

The G250 uses a solid cover with the small purge button in the middle. The S600 uses a soft rubber cover (that is in my opinion both homely and overly complex).

 

[bjpell]

So then for a safety point of view, it is easier in a panic situation to hit and find the purge button on the S600 then the G250. I went to my lds and looked at booth, I would not even consider the G250 for its small purge. If you were out of air (lungs not tank) and struggled with gloves to hit that purge your screwed. I like the larger purge but wish it was not so prone to freezing. Especially here in Michigan where ice diving is a quarter of the season for us. I will be buying the MK25/S600. The question is where, who is the cheapest with warranty.

What is this about an "AF kit"? does that stand for anti-freeze? where can I find that for this setup?

Thanks,

-=ben

 

[DA Aquamaster]

Well....I have dove since 1985 with "small" purge button equipped regs and have never had a problem. The purge on the G250 is plenty large enough. If you are prone to "panic" you may want to consider another sport.

In addition, the "small" purge and fixed cover of the G250 is quite an advantage in a current as it helps prevent the purge from being inadvertantly depressed by the pressure of the water flow in the current. Looking upstream with a reg with a full sized purge cover can be quite annnoying as your reg then freeflows.

The AF (anti-freeze) kit is standard on any MK 25 sold since June 2003, at least on regs sold by a Scubapro dealer. I am not sure how you would fair mail order. With LP for example, I have gotten some older stuff before rather than the latest and greatest.

The MK 25 AF works well with low pressure tanks and a G250. It works less well with the S600 and/or 3000 psi tanks.

Personally, I have had excellent luck with a TIS equipped MK 20 to which I also added a SPEC kit. I have been unable to get it to freeze even with sustained airflows in 32 degree water. It is however somewhat experimental, is not an SP approved modification, and adds some additional issues that need to be considered.