Great replies! One thing to add - You said you were brething on it, 'out of the water'.
Try it in the water. Also remember, an octo is a secondary air source. If you want exactly the same performance as your primary, then you will be paying the price for a primary.
William - Instructor

I agree with MAC your octo is going to be hanging there your entire dive. If they designed it to breathe as well as your primary it would constantly be free flowing during your dive. You want it to be a little hard to breathe and guess what, I guarantee no matter how bad it breathes now when it is in need you will suck hard enough to get the air out.

Regarding getting the exact same alternate air source (octo for some) as your primary...

If you are forced to switch to your alternate because of a failure with your primary, do you believe it's a good idea to be switching to a like second stage?

Doesn't it stand to reason that, given the environment you are in (for example cold) your identical alternate will fail for the same reason as your primary?

That's something to consider for purposes of redundancy. High quality yes. Testing it ona regular basis, yes. But it's worth considering to get something different than your primary.

Bruno

Hi,
many regs 'buzz' out of water...it what they do IN the water that counts!

I have a Mares Axis Octo on my AQUALUNG Titan reg, and BOTH breath equal - both perform VERY well, ESPECIALLY in the water! I think MARES makes high quality gear. SOME Octo's may breath a tad harder than you primary reg, so it doesn't FREE FLOW easily on you - also, could be your MARES Octo just need 'tuning.' Take it to a MARES dealer and have it looked at...MARES makes some fine stuff!

If your main regulator were to malfunction it would free-flow allowing you to breathe off of the free-flowing air to get to the surface. Another option is to switch to the octopus. Either way you can get safely to the surface. The main use of the octopus is not for your personal use but for the use of you buddy. If he didn't pay attention and lost track of his air pressure (dumb dumb dumb) He could switch to your safe second and get to the surface. The octo does not need to be matching brands, colors, or shapes. It just has to be there incase of emergency. Your octo will not breathe great but it does its job...

Your secondary octo should breath slughtly harder then your primary, as you do not want this to accidentally freef low during your dive.

Brad

Rebecca-- Don't forget that another acceptable method of air sharing is to keep the octo bungeed around your neck (so you can find it very quickly and hand your primary to your buddy. This also works if your buddy panics and forget's to tell you he's in trouble and rips your primary right out of your mouth.

And if they try to grab my bungeed octo, I'll nip at their fingers

Nightshade/TA: I actually use the same regulator I have as a primary as my octo. This is a Zeagle 50D. And to help with freeflow, there is a "switch" I can throw that keeps the venturi from "cracking" while in a current. The reason for this choice was that I desired to have the same performance in my secondary air source as I do with my primary. And my aim is to work toward dives that are a bit deeper and a bit more technical than your average recreational dive.

Another way of saying it is that I didn't skimp on my selection of a secondary air source. And I highly advise others not to skimp as well.

BTW, for an octo choice, investigate the Apeks TX40. These regs are getting very good "street" reviews and function well both as primary and secondary second stages.

I have the same Primary and Two Octo's. Cured my free flow problems with a Mouth piece ball. It looks like a tennis ball that fits tightly around and encloses your mouth piece on your reg. Keeps stuff out of your Octo also and make it easy to position your octo in the triangle. I have two octo's and a Spare Air I use them on with no free flow problems.

What a great cross-section of excellent answers.
Technically speaking, Mac8 hit the nail on the head regarding the "down tuned" octo. A stiffer setting does help prevent free flow. As recreational divers rarely use the octo, it doesn't need to breathe quite as easy as the primary. This is in no way to be construed that an octo should be cheap, never used or poorly maintained. It is a backup life support system for you and/or your buddy. I also deploy and use my octo frequently to insure its' reliability but don't usually finish the dive with it.

Different brands of primary and octo will not be an issue as long as the intermediate pressure is set within factory tolerances for both pieces of gear. Bright colors are of course wise for marking safety equipment.

There are those going deeper for longer periods of time who will adopt a higher standard for the performance of their gear in general. They spend more time and money on equipment appropriate for the environment they plan to be in - and most technical divers need to plan for the worst-case scenario.

I agree on 2 issues:
1. Your OCTO is tuned to breathe a tad harder than your primary reg - thats for a reason - you don't want it freeflowing while diving!

2. I agree as above - I am a DIR diver - and I too have my 'OCTO' (backup reg) on a piece of surgical tubing around my neck at all times - its MY backup - MY safe 2nd reg -in an OOA Emergency, I simply hand you MY primary (working reg in MY mouth) as: I know it works, its fairly cleared of water, I can get it to you in about 5 secs, and it is on a 5 ft LP hose so you will have plenty of space to work around in. In doing this - I KNOW you are getting a reg that WORKS right now - without leading to TASK LOADING (TASK LOADING kills divers!) and complications and wasted time while you get my OCTO free from its holder. My backup reg is NEVER dangling and is dragged in muck, mud or otherwise! Hope this helps!