Scubapro Second Stage w Apeks First? (unbalanced w/ overbalanced)

[mattimus]

Guys,

Am currently diving SP MK25/S550/R190 setup.

These regs breathe great but tend to ice up at depth and put on a nice bubble show. This really is no fun when your buddy (wife) dives the same regs!!

I am planning on swapping out at very least my first stage for an Apeks DST/DS4 or a Dive Rite first stage. What I am concerned about is whether or not my primary/octo will be compatible with these rigs.

I understand that my S550 second stage is balanced and should be compatible with the overbalanced first stage, but I am concerned about my R190 octo, which is unbalanced.

Has anyone miked a R190 with an Apeks (or other overbalanced first stage) and had any successes or failures that they would like to report? I'd really appreciate it. I'm not keen on having to drop big time coin on another reg set after dropping big time coin on this reg set just last year.

Thanks in advance,
Matt

 

[halocline]

It's possible you could solve the problem with a different SP 2nd stage, like the older G250 which has a metal barrel, or even just making sure your 1st stage is well tuned and the IP is low enough. I'd search for some threads about SP cold water problems and look for DA aquamaster's posts; you'll find lots of very useful info.

Regarding using the R190 on the apeks 1st stage, I'm sure it's fine, as long as the ports match. The only difference between the unbalanced and balanced aspects of the 1st stages is stability of IP at really low tank pressure. Another 1st stage option if you're interested in staying with SP would be the MK16, which apparently has none of the cold water issues the MK25 has had.

 

[divenutny]

Mattimus - I would do some more research before adding a non Overbalanced second stage to an Overbalanced first stage. If I understand the Overbalanced concept, the intermediate pressure increases with depth. So the non Overbalanced second stage will start leaking air at depths somewhere past 100 ft. If the Apeks is not overbalanced, any second stage that works with 140- 150 lbs range should work without fail. I recently bought a Apeks DS4/TX50. If is not overbalanced. There are many SB threads on this topic. Any LDS that handles Apeks/ Aqua Lung/ Us Diver should be able to determine if you have an Over balanced regulator

Good Luck - Tom

 

[cerich]

This guy is wrong. You could have free flow issues at depth with the overbalanced apeks and a un balanced second stage such as R190. Get a balanced second stage.

 

[DA Aquamaster]

In order to prevent an R190 from freeflowing at depth with an over balanced first stage, you would have to adjust the orifice to increase the cracking effort fairly significantly. This is however normally the case with octo second stages as they are usually set up with a cracking effort about 1" higher than the primary. Personally I don't agree with this approach, nor do I agree with having an octo with any less performance than your primary as the odds are very good that you will be breathing off it, not the OOA buddy.

 

[halocline]

Learn something new every day...

 

[do it easy]

I heard a rumor that the MK25's were set up for warmer water (higher IP pressure), and that they needed to be detuned to a lower IP for cooler water. I don't remember the recommended IP, but it would be worth looking into before you started buying new stages.