[Zbrafish] Sudden pH drop in system

tbartman from gmail.com via zbrafish%40net.bio.net (by tbartman from gmail.com)
Fri Mar 16 11:09:58 EST 2007

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

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.


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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