Today I added some fresh water to my tank, and within a couple of hours, all my livestock was dead. (Fish, snails and shrimp.)
Existing 220L tank that's been recently re-commssioned.
Moderate number of plants that have been in for either about a month, or about a fortnight.
New filtration, and all hardscape and glass cleaned with H2O2 or Milton. Anything that had been cleaned with Milton had had several days to dry off and then the tank was well rinsed before it was partly filled with dechlorinated water.
Akadama from previous instalation, probably with a decent culture of good bacteria.
At the weekend I was a little impatient, and as the water chemistry seemed ok (NO2 = 0ppm, NO3 < 20ppm), I transfered my livestock from a smaller tank I'd set up while the big one was recommisioned.
All seemed fine for a few days, and last night all the fish looked healthy and were very active. The world was good.
As the tank had only been about 60% filled, today I added some more water.
I used dechlorinator (which was well within it's expiration date) and heated the water to the same temp as the tank before adding it.
Within a couple of hours all the livestock was dead.
The dead fish were all still well coloured, weren't bloated or emaciated, and showed no external sign of infections.
As everything had been fine for several days, and then everything died very suddenly, I am assuming some sort of toxin, rather than a pathogen.
I tested the water for NO2 and NO3 again. All was fine.
I took samples of both the tank water, and the untreated tap water to the LFS, along with the dead fish. They tested the water and could see nothing that could explain such a catastrophic crash.
So ...
What now?
Obviously I'm reluctant to restock the tank without knowing what the problem is, and even then only very gradually.
Do I drain it and refill from scratch?
Do I leave it for a month and hope any toxin can be removed with regular water changes?
If I refill, what can I do to reduce the chances of it happening again?
Existing 220L tank that's been recently re-commssioned.
Moderate number of plants that have been in for either about a month, or about a fortnight.
New filtration, and all hardscape and glass cleaned with H2O2 or Milton. Anything that had been cleaned with Milton had had several days to dry off and then the tank was well rinsed before it was partly filled with dechlorinated water.
Akadama from previous instalation, probably with a decent culture of good bacteria.
At the weekend I was a little impatient, and as the water chemistry seemed ok (NO2 = 0ppm, NO3 < 20ppm), I transfered my livestock from a smaller tank I'd set up while the big one was recommisioned.
All seemed fine for a few days, and last night all the fish looked healthy and were very active. The world was good.
As the tank had only been about 60% filled, today I added some more water.
I used dechlorinator (which was well within it's expiration date) and heated the water to the same temp as the tank before adding it.
Within a couple of hours all the livestock was dead.
The dead fish were all still well coloured, weren't bloated or emaciated, and showed no external sign of infections.
As everything had been fine for several days, and then everything died very suddenly, I am assuming some sort of toxin, rather than a pathogen.
I tested the water for NO2 and NO3 again. All was fine.
I took samples of both the tank water, and the untreated tap water to the LFS, along with the dead fish. They tested the water and could see nothing that could explain such a catastrophic crash.
So ...
What now?
Obviously I'm reluctant to restock the tank without knowing what the problem is, and even then only very gradually.
Do I drain it and refill from scratch?
Do I leave it for a month and hope any toxin can be removed with regular water changes?
If I refill, what can I do to reduce the chances of it happening again?