[Zbrafish] Re: Sudden pH drop in system (tbartman@gmail.com)

Tiago Filipe Baptista da Rosa Repolho via zbrafish%40net.bio.net (by trepolho from bio.ua.pt)
Wed Mar 21 08:34:08 EST 2007

Hi Tom,

It is very strange to see such quick drop on pH values.
What you have to keep in mind is that carbonate hardness 
(KH) is the one that tells you the buffering capacity of 
your system.
You can even have higher conductivity values than the ones 
you wrote and still have low KH values.
To avoid "up´s and down´s" of your pH values, mantain KH 
values above 89ppm (at least).

Hope I was of some help,


Em Fri, 16 Mar 2007 12:00:12 -0500 (EST)
  zbrafish-request from oat.bio.indiana.edu escreveu:
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> Message: 1
> Date: 16 Mar 2007 09:09:58 -0700
>From: tbartman from gmail.com
> Subject: [Zbrafish] Sudden pH drop in system
> To: bionet-organisms-zebrafish from moderators.isc.org
> Message-ID: 
><1174061398.212811.293310 from d57g2000hsg.googlegroups.com>
> Content-Type: text/plain; charset="iso-8859-1"
> At my institution I have a main facility (which I 
>operate) as well as
> a small quarantine system (a single MBS rack - which our 
>Vet Services
> operates).
> On our quarantine system, supposedly the pH dropped from 
>around 7.0 to
> 2.0 over 24 hours, and all the fish on it died 
>(fortunately none were
> needed - they were only there to keep the biofilter 
>fed).  Vet
> Services states that no filter changes were done, and 
>they believe
> nothing else unusual was done.  The system had about 2 
>rows of tanks
> with water running (about 80 liters, plus the reservoir 
>volume), and
> about 100 adult fish.
> Can anyone think of any mechanism for the pH to drop so 
>drastically in
> 24 hours without human intervention?  The only way I 
>could imagine so
> few animals dropping the pH so quickly would be if there 
>were no
> buffering capacity, but the conductivity was steady at 
>500-600 uS.
> Are there any plausible explanations besides outside 
>addition of acid
> or a gradual decline that wasn't detected?
> Thanks for your tips.
> Tom
> Thomas Bartman, M.D., Ph.D.
> Divisions of Neonatology, Pulmonary Biology, and 
>Developmental Biology
> Cincinnati Children's Hospital Medical Center
> 3333 Burnet Ave, MLC 7009
> Cincinnati, OH  45229-3039
> Office: 513-636-9902
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Tiago Filipe Baptista da Rosa Repolho
Departamento de Biologia
Universidade de Aveiro
Campus de Santiago
3810 - 193
e-mail: trepolho from bio.ua.pt
web: http://www.bio.ua.pt/ZebraLab_UA_Webpage/Zebralab.htm

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