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Killed a tank with CO2

703 Views 3 Replies 3 Participants Last post by  fusiongt
I killed most of the fish in my tank last night with CO2. No worries, I did something stupid. However, I need to be clear that we are talking about a LOT of CO2, not just the regular "left it on in the dark" variety.


My question is with regards to the level of death I caused. I didn't take a PH reading of my tank after the incident, but I know that even with surface agitation and CO2 turned off...I haven't gotten the levels back down to the point I can add fish. (14 hours later)

Do I need to be concerned about the non-eukaryotes in my tank? In other words, have I nuked the bacteria and other minutia in my tank as well as the fish/snails/shrimp? Do I need to attempt to reintroduce them?
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I'd take a pH reading now. Bacteria won't grow under 5pH.

Do a 100% water change asap.
Wont reproduce or will die?

I dropped an aerator in and got it back up in the 6.5
My question is do I need to re-cycle the tank before I reintroduce fish?
Probably not. Test your nitrates/nitrite/ammonia if you want to be sure (should read low #, 0, 0 if it's cycled).

Worst possible scenario is you just kill them again and it's good for the industry. Have you learned the mistake you made?
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