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Lethal CO2

In December the Seachem Flourish Excel finished and I didn’t observe any effect after its application. I found a rest of the Tetra CO2 Plus. It supplies CO2 as the Seachem Flourish Excel. So, I used it. It was right before I flew to Barcelona. I returned on Christmas Eve and I was very shocked: One of the upside-down catfish (Synodontis schoutedeni) was dead caught at the filter. Then I noticed that 10 Cardinal tetras (Paracheirodon axelrodi) had disappeared. I didn’t understand what had happened. I though if the feeder supplied little food and the cardinals could have become prey. I didn’t have any explanation.

I cleaned up the aquarium on 6 January. I reduced the Anubias plant a bit and moved the wood a little such the plants had more space. At the time I applied everything as usually: eSha Pro-Phyl, eSha Optima, Easy Life Profito, Easy Life Kalium-Potassium, Easy Life Fosfo and Tetra Crypto-Dunge tablets. And added Tetra CO2 plus too.

On the following day I was shocked again. I found the other upside-down catfish dead. Then I observed that there were no cardinals. Five of them were caught by the filter. Then I found two at the surface. In that moment I didn’t understand what was going on. Maybe the filter? So I added one dose of Rataj BactoEsex. And I turned off the CO2 just in case.

Then I was thinking what I had done differently. I remembered that I had used Tetra CO2 Plus which I also used the first time the fish died. Its bottle indicates the validation until February 2019. It is possible as it is getting older it can become toxic for certain fish.

Tetra CO2 Plus

I found out something similar when I wanted to measure the NO3 by the Aquar Nitrat test. It expires in summer 2019. However, I’m not able to measure anything with it. The color does not change. On contrary the Rataj Azotin NO2 test which expired a year and a half, still measures.

Aquar Nitrat

Rataj Azotin



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