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Re: CO2 Response

> Date: Thu, 2 Nov 2000 19:35:30 -0800
> From: "Jeff Bodin" <bodin1 at gte_net>
> Subject: CO2 Response
> Up to the soap-box for one more minute...
> Wright write:
> "it was dangerously low and all here know that you get what you deserve..."
> That's a pretty brash (and nasty, "you get what you deserve") assumption

You are absolutely right, Jeff. It read that way to me when I re-read it, so
I admit to being guilty as charged.

For that, I offer my sincere apology. I just plain wasn't using good
judgement, and it showed. With hindsight and some reflection, I think I was
*so* upset at your loss of fish that I tended to take it out on you. Not
cool, anyway. Sorry.

> "We all know that a regulator gets squirrely when the liquid CO2 is all gone
> and tank pressure drops to near the regulator setting."
> Funny: When I left for work yesterday morning, the needle was still quite a
> ways out of the Red Zone. That indicated to me that there was still some
> time left. Red Zone to me means "danger". White Zone means (or should mean)
> "Still time left". And maybe you know, but obviously, "We all" don't.

Same problem. Same guy is guilty.

Mine do, as I recall, go into red at 600 psi. IMO, any drop below 800 is
time for a change, as the tiny bit of gas left will not last very long.

> "What a pity the digest rejects attachments. You have my curiosity aroused!"
> I will take this as an attempt at softening what was at first appearing to
> be a demeaning response. And that you would actually got curious about me
> being up-side-down and naked has me more than a little concerned (and that's
> supposed to my attempt at humor, not a personal jab).


snip... More rude prose.

> "The deaths were probably due to the high fish count, coupled with nitrites
> and inadequate buffering, or maybe simple suffocation if hood was unvented,
> when the last of the CO2 went out faster than normal. Blaming it on a
> product that was working exactly as it should will not make you appear to be
> wise, here."
> a) Fish count was borderline on the high side.
> b) Zero Nitrites
> c) Hood has 4"x48" of ventilation across the back (Plenty in my book)
> d) You missed the main point: I was told by the seller that this system was
> safe and would not do this because of the way he designed it.

And I'll back off my initial conjecture. CO2 isn't harmful at the 10-15 ppm
levels we normally use. It does cause acidosis and severe blood problems at
levels consideably higher than that, say 100 ppm. You probably had a good,
big release, through an efficient diffuser to be able to kill all the fish.

If the vendor told you that, I'm a little surprised, but it may have been a
different one from where I got mine. He was explicit about the low pressure
problem to me. Sounds like your source created a bit of liability for
himself, to me.

> "Using a spring-loaded check valve as a final pressure reduction is a sure
> way to get a major overload of CO2 in the final 30 psi or so, if you have
> not monitored and changed the tank. "
> Funny. When I first got the system, it was missing the check valve. I ran it
> without it and then called the seller. The seller went on to explain that
> without the check valve I would kill my fish. So the seller sent me a one
> and I installed it. Hahahaha.

No. Grrrr!

> So,  In conclusion of this thread (my last word on this topic at least)
> a) Never make the assumption that everyone on this list follows every thread
> and we all know it all because someone else does. It's demeaning,
> condescending and shows pettiness to those who are new (or old) and want to
> feel free to comment.

Agreed and I apologize again, for you are absolutely correct.

> b) I'm gonna monitor that tank better because of this.
> c) Needle valve on order.

That should do it. A proper-size needle valve is a true flow regulator, and
a few psi input pressure change will hardly affect the output flow at all.

A check valve, with a strong spring, as comes with the Eheim diffuser, acts
like a really, really poor second *pressure* regulator. It drops the amount
of pressure needed to open the spring flap, and that can be up in the proper
range of adjustment of a normal regulator. The outlet side is at whatever
pressure it takes to push CO2 through the depth of water you have (usually
too low for the regulator). Setting the bubble rate is mighty difficult,
because there is no real flow-rate regulator there. You must set the
regulator pressure to precisely the sum of the two back pressures (spring
and water depth), and it takes me a couple of days to get it right.

A regulator running at 15 psi output will hold that nicely, and only rise a
few psi as the pressure drops and regulation is lost. At 18-20 psi, a *lot*
of gas can dump through that spring-loaded valve, as you can see if you test
it and just set the pressure that high with the regulator adjustment.

Good that you are going to a needle valve. 

Use soft silicone hose between the regulator and the needle valve, as a
pop-off pressure relief if the valve ever gets clogged. Most folks
assembling CO2 regulators do a "no-no" and use teflon tape instead of joint
compound, which means a thread can always break loose and clog the needle
valve. Any tiny leakage in the regulator diaphragm can then allow high
pressure at nearly no flow, that downstream components are not rated for.
Regulators need a little flow to work properly. Blockage can be dangerous.



Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot com