MK2+/R390 as an 'octopus' reg?

I'm planning on using R390 octo from my MK25AF/X650 setup, and getting a MK2+ to be used as a redundant reg (in combination with the already mentioned R390) on a single tank.

Since my dives are within recreational depths, and I don't see myself venturing into tech diving any time soon, I'm just curious, does this makes sense?

It seems like more sound thing to do then just attaching another 2nd stage on the same 1st stage (even if it means adding another possible point of failure).

Any suggestions, perhaps a different 1st stage (MK11/MK17?) would serve better for such purpose? How would the MK2+ breathe at the depth of 35-40 meters? In an OOA situation, I'd be the one using this regulator to breathe from, as I would donate my primary.



Scubapro is my preferred brand since I can have it serviced nearby, and Italy is one hour drive away. Integrated inflator/octo combination is out of the question.

A Mk 2 Plus R190 will work well at recreational depths. You will definitely notice the performance difference between it and your Mk 25 X650, but it will get you to the surface just fine.

I tend to agree a pony bottle makes more sense than an octo on your primary regulator as it gives you a fully redundant gas supply. Also, if you donate air to another diver or switch to it after your primary fails, the dive is over and you are ascending anyway so there is no rec situation where 2 divers would need the larger capacity of the primary tank.

Just be sure your pony tank is large enough to be useful (19 cu ft or better - not sure that that is in liters)

Got a good price for the whole system as they are being replaced with MK2+/R295 systems, so I took it all...

I now have the following:

MK25/X650/R390 octo
MK2+/R290

As I understand, R390 and R290 are basically identical, only that R290 lacks the user adjustable knob, while the R390 has it (dive/predive).

Does this really make such a difference that I should transfer the R390 onto MK2?

I think not, and that R390 goes in the closet as a spare octo should it be needed someday (plus it has the ugly yellow purge cover ).

Absolutely... the MK2+ R390 setup sounds perfect for what you need. In an ooa situation, reliability is definitely key and the MK2+ R390 will provide that for you.

DA Aquamaster:

Just be sure your pony tank is large enough to be useful (19 cu ft or better - not sure that that is in liters)

Click to expand...

19 cu ft= 538 liters@207 bar(3000psi) which means a water capacity = 2.60 Liters