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Tetra CO2 System


  1. Tetra CO2 System? Lights?
    by booth-at-hplvec.LVLD.HP.COM (George Booth) (Wed, 2 Sep 1992)
  2. Tetra CO2 System? Lights?
    by (S.P.Zeidler) (6 Sep 92)
  3. DIY-CO2 and "Tetra Bells"
    by (Todd O'Brien) (26 Jan 1994)
  4. CO2 Diffusion area
    by George Booth <booth/> (Sun, 30 Apr 2000)

Tetra CO2 System? Lights?

by booth-at-hplvec.LVLD.HP.COM (George Booth)
Date: Wed, 2 Sep 1992
Newsgroup: rec.aquaria

In rec.aquaria, (Bill Stapleton) writes:

 I was surprised to see a Tetra CO2 injection system in the store last night.
 I didn't see much of it - They were apparently using it in a couple of tanks,
 but only the plastic "bells" inside the tank were visible.  I saw the "master
 kit", in a box, in a display case, with a $250 price tag.  That's about all I

  Anybody using this, or know much about it?  I assume it's very similar to the
  Dupla system?

The local store was tapped as the exclusive local retailer for the Tetra
system, but blew it off as soon as they saw it.  From what they said, 
it is a small CO2 canister (that only the Tetra retailer can refill),
a manual valve and a bell-jar like thing that you fill with CO2 via 
the valve whenever it needs filling (like 3 or 4 times a day).  A "test
kit" was also part of the set up (maybe an extra cost option).  

They have experience with CO2 (I taught'em everything they know :-) and
felt the system was a joke.  Too little, too manual, way too exepensive,
way too much trouble for them to refill. They tried the test kit - it said 
"too little" or "too much" and said their CO2 level (15 ppm) was "too much".  

The Dupla kit is *not* the same.  It can be attached to a real, U.S. style
CO2 bottle and uses a fairly sophisticated diffuser/check valve setup.  The
included "Continuous CO2 Test" shows "too little", "just right" or "too much"
but seems better calibrated than the Tetra version - and it stays in the
tank so just a glance will tell you what's up.  

You can get a much better set up than either of these for about $150 by
shopping welding supply stores and using a little Yankee ingenuity.


Tetra CO2 System? Lights?

by (S.P.Zeidler)
Date: 6 Sep 92
Newsgroup: rec.aquaria

>In rec.aquaria, (Bill Stapleton) writes:
>I was surprised to see a Tetra CO2 injection system in the store last night.
>I didn't see much of it - They were apparently using it in a couple of tanks,
>but only the plastic "bells" inside the tank were visible.  I saw the "master
>kit", in a box, in a display case, with a $250 price tag.  That's about all I

Is this the kit that contains a CO2 diffusion bell, some CO2-tight tubing
and a hair-spray sized can with CO2, to be operated manually ?
Are you sure the price tag wasn't really $25 ? The stuff I described is
the only Tetra CO2 kit I have seen yet (which doesn't say that much), and
that comes for 35DM at the local fish-shop, refill can for about 10DM
if I remember right. The kit is for <= 50l (10gl) tanks, where a
'real' CO2 kit would cost more than the rest of the tank together.
Dennerle makes something that looks much the same, but has continuous
CO2 supply (guess follows) coming from some yeast munching away
at a blue-colored sugar gel, at a slightly higher price.

        spz is S.Petra Zeidler  Copyright 1992 S.Petra Zeidler  
 MPI fuer Radioastronomie Bonn  
    Auf dem Huegel 69, Germany  reading prescription: cum kilo salis

DIY-CO2 and "Tetra Bells"

by (Todd O'Brien)
Date: 26 Jan 1994

First of all, I want to completely thank Thomas Narten (
for posting the original "DIY-CO2" articles.  The following is only in
to questions about my use of the Tetra CO2 System "diffusion bells"...
All credit goes to Thomas Narten (and the people he in turn thanked) for the 
initiation of my adventure in DIY-CO2 ... 

What is the "Tetra CO2 Bell" ?
        Are you familiar with the $400 ($225 TFP price) Tetra CO2 Master Kit
that comes with a CO2 tank and regulator and four diffusing chambers (or as
I called them, bells... oops!).  On page 8 of the latest (blue) That Fish
Place catalog, under CO2 systems, they sell "CO2 System Add on diffusing
Chambers, 2/pk.  $8.99".  That's what I bought.  I got them at the local pet
store for $9.99 (but think it was a mistake and they should have been $14.99).
It is just two clear plastic bells (er, diffusing chambers) that attach to an
airline (from your CO2 source) and then suction cup to the side of your glass.

The "Tetra intended use" is to fill them twice a day (fill 2 bells for up to 
30 gallons, fill 4 bells for up to 55 gallons) with CO2 from their over-priced
regulator and puny 7 ounce tank!  The gas trapped under the water, is pressed 
on by the water, and diffuses into the water.  

I originally saw them offered in 2 packs in the TFP catalog, and found my 
fish store had them.  So I bought them.  They look nice, apparently work, and
appear to regulate the CO2 diffusion such that my pH isn't flying.  *I have
not done a CO2 concentration test yet, but my plants are growing noticeably
each day!!!*  The best thing is that I don't have to build my own diffusor,
or look at an ugly plant pot or bottle top every day.  Simple, not expensive,
and aesthetically pleasing.

How to Hook them Up ...

FOLLOW THIS VERY CAREFULLY!  Remove the diffusing chambers (bells) from the 
box.  Hook the CO2 airline (from the DIY-CO2 article) to the top of the bell.
Put bell in water, turn upside down (to escape all trapped air), turn right
side up, and attach to glass.  (If you can't manage this, give up the
fish hobby completely! (And yes, I'm being sarcastic!))

How to Use Them ...

Tetra intended them to be used by filling them twice a day from their tank.  
Since my yeast generator is so slow (3-4 bubbles per minute), I leave them 
"filling" all day since the diffusion rate is almost the same rate as the
filling rate.  I also use a powerhead (100gph) aimed at the bells from about
14" away to speed the diffusion and mixing into the water.  While I at first
used gang valves to turn the CO2 on and off at night (on equals into the
chamber, off equals into the air (ie. escaping)), I got lazy and now leave
it on 24 hours.  At night, however, I turn on a media-empty powerfilter
(Whisper 100) to oxygenate the water and purposely off-gas the CO2 (it's on a
timer that counters my light timer).

So far, my pH is not dropping (inspite of my "no buffering Boston Water"). 
my plants look beautiful (noticeably growing each day!).  I am on day 5, and 
I'll keep people posted if the pH crashes ...  This is the only thing I am 
nervous about, but can easily be fixed by not filling the bells 24 hours a
day ... :)

My DIY-CO2 set-up ...  (Refer to Thomas Narten's posting for more info!)

I used Fleischmanns "50% faster" yeast.  I tried the recommended 1 teaspoon
but it bubbled like an airump and burned out in one day.  I tried the same
set-up with only 1/4 teaspoon of this yeast and it is going strong at 3-4
bubbles per minute on day 5.  Experiment for yourselves ...  

Good Luck.  This stuff works!  I went from being the "black thumb of aquatic
plant death" to the "green thumb of growing aquatic plants" in one day!

CO2 Diffusion area

by George Booth <booth/>
Date: Sun, 30 Apr 2000

>Date: Wed, 26 Apr 2000 22:58:33 -0500
>From: "Dustin Swanson" <>

>I was wondering if there's a general formula or chart for the surface area
>of the CO2 in the "bell" that should come in contact with the water based on
>the size of the tank.  

There is such a table in "The Complete Book of Aquarium Plants" by Allgayer
and Teton. It shows surface area in cm^2 needed based on KH and tank volume
in liters. 

For a typical value of 5 dKH, surface areas are as follows:

Volume:  1,000   800   600   400   200   100 
Area:      180   140    80    50    30     *

For a value of 3 dKH, 

Volume:  1,000   800   600   400   200   100 
Area:      140    90    40    40     *     *

* CO2 produced by fish is sufficient under normal circumstances

George Booth, Ft. Collins, Colorado

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