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Old July 16th 04, 02:19 AM
Bill K
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Default HELP massive fish die-off

On Wed, 14 Jul 2004 01:12:01 -0400, "NetMax"
wrote:

"Bill K" wrote in message
.. .
I had the unfortunate incident of a massive fish die-off in my tank
this weekend.

I'm after 4 things...

1) What happened?

The presence of nitrites (2ppm) either indicates an ammonia spike occured
earlier, or the nitrite oxidizing bacteria were inhibited (nitrobacter is
more strongly affected by loss dissolved oxygen than nitrosomonas). If
ammonia spike, this would be partly responsible for the stress on the
fish. Having the pump off (2 hours and them 5 hours) would indicate that
the O2 levels would have dropped during these periods. The 5 hours the
filter was off would be sufficient for the bacteria to go anaerobic. The
fish could have been exposed to the noxious water put into the tank from
the filter, after riding an ammonia spike, and during lower than normal
O2 levels (a 3 punch knockout with a moderately loaded tank?)

....

This is mostly speculation. You could easily have suffered from a pH
crash, and after so many water changes, your pH would have been normal,
or there was nothing you did which was significant enough, and an O2
difficiency (algae bloom?) or some chemicals (high chlorine levels) were
present and with massive water changes, responsible. Sorry for your
loss.

snip


Thanks to all who responded. My final conclusion is probably a
combination of factors, I think NetMax is correct.

I'll never know, but I have learned to be a LOT more careful when it
comes to ever doing this again. Yes, the canister pump should not of
been off that long, even if it meant running through the tub of water
where I had stored the plants... just to keep the bacteria oxygenated.

And, without knowing how effective (i.e. speed and completeness) the
AquaPlus chlorine remover is, I might not of given enough time for the
Chlorine to be removed (I know we don't use Chloramine in our water..
yet) in such a large water change.

As a final note I heard back from the civic water technician. We had
a very pleasant and lengthy conversation. The alga bloom had no
effect on the water supply. At least not with regards to Ammonia,
Nitrite, Nitrate or other levels of toxins.

He was a great guy to talk to and we discussed the City's decision to
go to Chloramine next year. He wasn't too surprised by my call. He
related a story from a couple of years previous where a woman had lost
her Oscar of a dozen years and was quite distraught thinking that
maybe the water had an effect.

(now on to my other posts.... Melanotaenia, boesmani or praecox and
Kribs (how many) or Bolivian Rams).

I try to think of this as an opportunity to alter our stock as we
re-populate the tank.

Again... thanks to all.

.... Bill