[Prev][Next][Index]

fw:Re: High CO2

Forwarded from stevensj.

-Shaji
-------------------------------------------------------------------------
Shaji Bhaskar                                              bhaskar at bnr_ca
BNR, 35 Davis Dr., RTP, NC 27709, USA                      (919) 991 7125

---forwarded message---->

From: stevensj at calshp_cals.wisc.edu
Subject: Re: High CO2
Date: Sun, 16 Jul 95 8:47:22 CDT
Mailer: Elm [revision: 70.85.2.1]

>  Subject: HELP! High CO2
> 
>  Jayme,
> 
> I am not sure what happened to Joanne's tank, though I suspect that she was
>playing with different buffering systems using peat, a Seachem buffer of
>unknown origin, and and the carbonate buffering system familiar to us users of
>supplemental CO2.  I would question the reliability of CO2 reading under these
>circumstances.

I agree that mixing buffers was not a good idea & I won't be trying that again!

>
> What ever the cause, I question some of your advice.
>
> >> TRY:  I would immediately  lower the PH to BELOW 7.0 to *reduce* the 
>toxicity level of the Ammonia (I would say 6.7-6.7).  Ammonia is less toxic at
>lower PH levels (below 7.0). <<
>
> >> Suspend use of your CO2 injector completely for now. <<
>
> While it is true that the ammonium present at a pH below neutral is less
>toxic than ammonia, (and more easily used by the plants) if you want her to
>suspend use of supplemental CO2, how do you propose that she go about lowering
>the pH in the tank?
>

I just wanted to comment that removal of the CO2 system & a 30% water change
(though this was with hard, alkaline tap water) did seem to help at first
since the fish no longer hovered at the surface, but a few hours later two
were dead.

> Also, I'd like to point out that on a tank adjusted to steady application of
>supplemental CO2, the change to no supplemental CO2 is adding yet another
>instability to an already unstable environment.
>
> While Joanne's 40ppm of CO2, (if it really was that high, considering the
>other chemicals in the "brew" at that point) while high was not out of the
>range considered to be tolerable to most fish.  I suspect it was the rapid
>change in the amount of CO2, and the resultant rapid pH shift that caused her
>fish distress, along with whatever decay process caused her ammonia level to
>spike and, probably, her O2 levels to fall as well.

I am pretty sure that the 40 ppm reading was accurate.  I am sure that this
is what caused the fish to hover at the surface, the only other thing I can 
think may have been a problem was too low O2.  I measured nitrite in that tank
that morning & it was normal.  After the water change & fish deaths it became
elevated.  In that same tank this morning, before the lights turned on I
measured O2 and it was about 5ppm (lower than one of my tanks with UGF which
was about 8 ppm), CO2 was 17 ppm and nitrites are still elevated (ammonia is
zero though).  I put on a pump with airstone to increase O2.  I also put the
old yeast + sugar bottle on yesterday & I put new mixture in today to try to
keep the CO2 high (between 15 & 20 ppm hopefully) even though I have the
airstone on.  I will monitor O2 levels.  I think it will only be neccessary
to run the O2 at night, but I'll run it today as well, just to get the O2
up to 8 ppm.

> 
> >> Making water changes aggrevated the situation by diluting the percentage
>(amount) of Nitro-Bacter in the water. <<
>
> Nitritrifying bacteria (whether we are discussing nitrobacter or
>nitrosomonas) are, to my knowledge, not free floating bacteria, but attached
>to a substrate. (be it aquarium gravel, plants or the glass walls themselves)
>Water changes unless in done with water toxic to the bacteria should not
>interfere with the nitrogen cycle.
>

I'm still not too sure what upset my nitrogen cycle - possibly the bacteria
were killed due to high CO2 just like two of the fish were (anyone know how
sensitive bacteria are to high CO2 levels?).  I did notice yesterday, when
I did a partial water change and rinsed the filters in old water, that the
filters were quite gummed up (the buffer gave everything a slimy feel/coating).

> >> If you didn't rinse the Carbon Insert/Cartridge for the Powerfilter, that
>will also  introduce Carbon Dust into the water, which creates Carbonic Acid.
><<
>

I did rinse the carbon, but carbon is pretty inert.  It is CO2 that reacts with
H2O to form carbonic acid.

> I have never heard that!  This would mean that the carbon containing diatom
>filter powders would cause the same problem.  I find this highly unlikely!
>

Joanne.