CO2 problems

On Mon, 17 Jul 95  "David Huie" <David.Huie at Bentley_COM> wrote the following
re: Yeast Explosion
>     I have a problem that I'm hoping someone can give me suggestions on.
>     I've had all the fish in my tank killed by acidosis...twice now.  Both 
>     times were as a result of massive pH changes due to my inaccurate CO2 
>     injection method.
It sounds like this may also be due to inadequate buffering.  What is your

>     The first time, the tank just ran out and the pH went from 6.2 to 7.8 
>     in about two hours.
Hmmm ... wouldnit that be alkalosis (sorry, just being picky)
>     The second time, last week the whole CO2 tank vented into the aquarium 
>     at once--a one inch shell of ice on the CO2 canister was a bit 
>     bizarre.
>     I have my CO2 canister, through a regulator, pumped into the input on 
>     my pump.  The pump is connected to a 1/2" hosee which is connected to 
>     a PVC pipe with sponges inside (hanging vertically).  The water is 
>     forced vertically down into the vertically-oriented chamber with 
>     sponges inside...it slows down the CO2's escape and traps some of the 
>     bubbles in the sponge.  I think what happend was that the sponges got 
>     clogged with mulm and during a short power outage, with the pump 
>     stopped, a pressure release event like my yeast explosion 
>     happened--the pressure built-up behind the plugged-sponges eventually 
>     blew the intake off of the pump and vented the entire canister of CO2 
>     into my tank...the pH was something lower than 5.5 (the lowest my kit 
>     will measure) and all my expensive fish (including about 10 siamese 
>     flying foxes which cost $8 + shipping ea.) were floating uncontentedly 
>     belly-up.
I'm thinking that this may be a good argument to go with a less efficient
CO2 chamber such as an upturned soda bottle bottom, so that no clogging
can really occur and you can see changes in CO2 entering the tank a bit
more easily & an overflow would just bubble out the bottom & out of the
tank fairly easily.  It may cost you more in CO2 but less in fish.

>     It hasn't killed any of the plants yet, but the crypts are feeling the 
>     strain.  I haven't had any CO2 in the tank for about a week now and I 
>     really have to wonder what to do.
>     I won't cope with another mass fish death due to massive pH 
>     fluxuations and I don't think I can afford a fully-automated CO2 
>     injection system--and I won't go back to my old unreliable yeast 
>     method.  Isn't there a reasonably affordable reaction chamber 
>     available to help dissolve CO2?  Even That Fish Place claimed to have 
>     no such thing.  I had to makeshift--and it turned out to be the death 
>     of my fish.
The tetra diffusion chambers are something like $8 each, but maybe these
are too inefficient for you?  I had no problems with pH fluctuations
using them in my 125 gal tank.  I had 4 CO2 bottles running though, all
at different stages so it kept CO2 more constant than in my smaller tanks.

>     I will no longer keep expensive fish because I can't afford to replace 
>     them.  I have two 10 lb. CO2 tanks and a regulator--anything I can do 
>     that will make a reliable system for $100 or less?
I don't think the expense of the fish counts as much as the sensitivity
of it.  Though ... I have heard/read that clown loaches are very sensitive
to nitrite, but mine survived my recent ups & downs with CO2 as did corydoras
catfish, clown pleco, kuhli loach & fancy guppies.  My angelfish & fire-eel
proved to be too sensitive.  I was thinking about getting some SAE's for that
tank cause it has a slight hair algae problem, but maybe I'll try oto's
instead if SAE's are too sensitive.
>     Thanks in advance.
>     Dave

I just wanted to also let you all know that last night I accidentally turned
down the airpump on my 10 gal tank (this tank has just an UGF but is
very stable usually & was the tank I put my fish in from my problem tank
last week) ... Anyway ... this morning I noticed what I'd done & turned the 
air pump back up (it powers two airstones that power the UGF) and I decided
to take some measurements even though the fish looked fine & there looked
to be no problems from my actions.  The CO2 measured 45 ppm and the O2
measured about 5 ppm.  Now this got me thinking that perhaps my problems
last week were not due to high CO2 but very low O2.  Last week I did not
measure O2 in the tank till a few days after the high CO2 incident when
CO2 levels wer back down to normal - but even then the O2 was 5ppm. It
seems quite possible to me that the O2 was extremely low earlier & that
may have been what killed the fish & upset the N cycle.

I would like to thank everyone for their advice.  I'm glad things are OK
now but I'm still trying to figure out just exactly what went wrong :-).