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Re: THAT's IT!!! (CO2 systems)

> Date: Wed, 1 Nov 2000 21:04:22 -0800
> From: "The Bodin's" <bodin1 at gte_net>
> Subject: THAT's IT!!! (CO2 systems)
> Well,Just when I get all other areas of my tank where I want them...
> This gang can argue all they want about high-pressure vs. low pressure CO2
> systems, but I have just had an all-fish death due to the "dump" of a
> "High-Pressure" system. I had 400 lbs of CO2 when I left for work this
> morning and tonight the can is empty. 

I seriously doubt if you had "400 lbs" of CO2 left. You probably had less
than a half a pound. If the guage read 400 psi, it was dangerously low and
all here know that you get what you deserve if you let it stay on when
pressure gets below about 600 psi (i.e., all the liquid is gone and you are
running on fumes).

> You can advertise all you want about
> how "safe" this type of system is if properly set up right, but the facts
> are if a system is safe it should NEVER (EVER!) do this.


We all know that a regulator gets squirrely when the liquid CO2 is all gone
and tank pressure drops to near the regulator setting. As soon as the
pressure is below 800 psi, you need to take the tank off line and get it
refilled. Weigh it before a vacation to be sure it will not run out while
you are gone.

We also don't believe they are "safe" in the sense you mean of "idiot
proof." Gas/liquid under high pressure is *alway* a potential hazard,
requiring adult supervision and strong methods to keep kiddy hands from

> No matter what anyone says ever again on this list I will stand on my head
> naked (and no one wants to see that, believe me) 

What a pity the digest rejects attachments. You have my curiosity aroused!

> before I'll ever have
> anything positive to say about this type of system. I will also freverently
> anti-market this system because of this experience. This sucker is going in
> the garbage.

It's still has vestiges of being a free country, so do as you please (until
the PC thought police arrive). You will not get a terribly sympathetic ear,
here, from folks who have bothered to read the digest or archives on the

> Death toll is:
> 3 Large Discus (Best red Discus I've Ever seen, too)
> 20-30 Cardinals
> 20-30 Rummy nose
> 3 SAEs and,
> several OTOs

That's a definite, unqualified "Oh Tshidt." if you'll pardon my Russian.

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.

I sympathize with such a terrible loss, and certainly wouldn't want that to
happen to one of my tanks. Unless we knew the size of the tank, type of
reactor/injector, amount of plants, KH/nitrite level and how well the hood
was ventilated, it is difficult to suggest a way to avoid it in the future
that makes sense for your situation, unless you learn to never run a tank

The excess CO2 alone will not kill the fish. Suffocation and nitrite
poisoning are possible culprits when CO2 gets too high and pH gets lower
than normal.

I've had a tank dump with no adverse consequences to my fish. [We all have a
learning curve, and I was just lucky.] My covers weren't very tight, and my
water was moderately hard, with quite a bit of buffering. The fish load was
quite low. I was even running an outside biowheel, that served to stabilize
and oxygenate the water.

> Anyone want a high-pressure system now! I have one for cheap! I could also
> use a reccomendation on a real "fail-safe" system, and if it is back to
> yeast/sugar, so be it.

A fail-safe *unattended* system consists of a second, low-pressure
regulator, following the regulator in your system. The ones used for
domestic gas delivery are perfect for this (if a bit big and ugly).

I'll take that cheap system off your hands, if you want to contact me off

> Am I Pixxxx?!?!?! You bet. Especially at the people/persons who sell these
> things (sold one to me) and brag at how safe they are. If anyone has any
> links to where I can get a more reliable system, please feel free to contact
> me off-line.

Most of us have fail-safe systems by involving the owner in monitoring tank
weight or pressure, and replacing it as needed. We never, ever let the
pressure get down below 400 psi, for we know the last of the CO2 will blow
out with any normal regulator, unless we are metering the final flow with a
really good needle valve. If we use an Eheim diffuser, we know the Eheim
check-valve isn't a good flow restrictor if the regulator pressure goes up a
few psi at end of tank.

We sympathise with your loss, Jeff, but I'm inclined to think your loss was
because we beat the subject to death so much here that the finding of a few
grains of truth among the chaff may be more than folks should have to do.

CO2 tanks dump, with a single regulator -- some worse than others, but all
do it. As the liquid all evaporates, the pressure drops quickly from 800-900
psi, and the regulator loses control down somewhere below 50 psi. There's
just a little gas left, but it can unload quickly if you have no real flow

Using a needle-valve as the flow restrictor, after the regulator, is a
fairly fail-safe method.

Using a second regulator (AKA two-stage regulator) can be made to be very
safe, with a little design cleverness. The needle valve is about as
effective, and much cheaper and less bulky.

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. 

It is still the method I currently use, and I see nothing wrong with it as
long as I understand that the regulator output *will* go up a few psi on
emptying the tank, and the check valve will allow a huge flow increase at
that time. Moral: Change before empty.


PS. I've done far worse damage to tanks by a tipped-over yeast bottle
forcing solution into the tank than any high-pressure accidents I have had. 

Moral 2: Invent a more idiot-proof system and they'll invent a better idiot.


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

         "Ignorance creates a fertile climate for demagogues;
         maybe that's why politicians give so much support to
                the public education establishment."
                                              Walter Williams
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