Neil Woodman wrote:
Nikki Casali wrote:
Neil Woodman wrote:
Hi,
If wonder if any of you guys could help me. I did my usual 30% water
change on Saturday night, I got in on sunday to find all of my tetras
swimming near the surface gasping for air, the only thing I had done
differently was increase the CO2 slightly. Then I noticed some
bleeding heart tetras were dead, and then I noticed some shrimp going
a bit strange darting up to the surface and back down again. Suddenly
all the fish started to die in front of my eyes! There was obviously
no oxygen in the water so I added a powerhead to create some surface
agitation and did a 50% water change. The tank has now gone really
cloudy and I've lost most of my tetras and shrimp, there are only
some ottos, a 4 tetras, a rabble of shrimp and one ram which is hard
as nails left alive. So this morning I rushed to my local aquatic
shop. He asked me if the water had gone cloudy after I explained what
happened and it had, so he then said it was a breakdown in the filter
which has caused all the bacteria to go into the water, which had in
turn suffocated all the fish, he recommended doing a big water change
which I had already done and recommended I use some filter aid to
clump together the particles to filter them out faster, I cant
remember exactly what he said but it was along those lines. Can you
guys explain what might have happened and why? This has never
happened to me before and I've been keeping fish for a long time, to
suddenly see them dying in front of my eyes has been a harrowing
experience.
I use an external filter and pressurised CO2, I dont know if that's
anything to do with it, the tank is heavily planted.
I'm very sad about what has happened.
Do you have any idea what the CO2 level was or the pH? Is the change
water straight from the tap and do you allow the water to stand to
allow noxious gasses to dissipate? My tap water contains high amounts
of CO2 etc. Why do you do large water changes?
A breakdown in the filter causes all the bacteria to go into the
water? I don't think so. The bacteria are already in the water. Did
your filter jam up? You didn't make this clear.
Nikki
Hi,
Thanks for that.
CO2 was about 1 bubble per second or so, ph was about 6.5.
What are your KH and GH? What size is your tank? I presume you live in
the north of UK where water is softer? I live in London. A pH of 6.5 for
London water would indicate dangerous levels of CO2. I bubble 2 a
second. This is enough for my 330L tank to reach a pH of 7.25 from 8.1
with masses of plants.
Although the
test kit I have doesn't really measure that accurately in terms of range
my ph indicator I have permanently setup showed nothing untoward. My tap
water has always been ok bar a high level of phosphate, which I use
rowaphos to remove, I'm thinking the rowaphos suddenly released all the
phosphate it had stored up due to it being totally saturated and used
up, I've heard that can happen.
Rowaphos state that releasing all its contents is something it does not
or cannot do. I've used Rowaphos in the past with no trouble.
There seems to be nothing wrong with the filter but the water has gone
really cloudy, I have 4 fish left which are still alive but my shrimp
are perched on top of the inside edge of the tank, literally out of the
water! They don't look too happy either.
My shrimp hate water changes. They go berserk, especially if the water
has come from the copper hot water cylinder.
I have always done large water changes as I do about 30% per week, is
this wrong?
It really depends on the compatibility of your tap water with settled
tank water. My tap water comes out at 7.2 pH. My non-CO2 injected tank
stays at 8.1 pH. So if I'm making big changes to that tank I allow the
water to dissipate its CO2 by bubbling with an air stone until the pH is
closer.
Just a guess, but if your tap water contained a high level of CO2 and
you changed the CO2 bubble rate at the same time this combination could
have given your tank pH a kick to a dangerous lower level.
Regarding pouring dechlorinated tap water into your external filter. I'd
never do it. This could possibly have had the effect you see.
Nikki
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