Sudden Nitrite Boom

[ghostchoir]

I'm not sure why, but my more established tank that has been running perfectly for a few months has now had a nitrite boom. The tank is 125 litres with 6 cories and 10 tetras, I'm not sure why it happened. The levels have all been at zero for the last few months and a water change was only done on Monday! (we do them once a week)

One of the cories died yesterday and though I got his little body out as soon as I noticed (which didn't take long as I was already keeping an eye on him ) could this be what has caused it?

Before anyone asks, I use the 'professional' dropper test kits and I usually check twice a week.

Nitrate: 12.5 mg/l
Ammonia: 0
Nitrite: 0.8 mg/l

I'm really not sure why it got so high so suddenly so I'm assuming it HAS to be beacause of the dead cory. Is this why, or am I missing something here?

Either way, what is the best plan of action? I was planning on doing a 50litre change in a few hours when my boyfriend gets home (because I am a weekling and cannot carry the water buckets ) but would this be too much considering I only changed the water two days ago?

 

[Bullrock74]

I'm not sure why, but my more established tank that has been running perfectly for a few months has now had a nitrite boom. The tank is 125 litres with 6 cories and 10 tetras, I'm not sure why it happened. The levels have all been at zero for the last few months and a water change was only done on Monday! (we do them once a week)

One of the cories died yesterday and though I got his little body out as soon as I noticed (which didn't take long as I was already keeping an eye on him ) could this be what has caused it?

Before anyone asks, I use the 'professional' dropper test kits and I usually check twice a week.

Nitrate: 12.5 mg/l
Ammonia: 0
Nitrite: 0.8 mg/l

I'm really not sure why it got so high so suddenly so I'm assuming it HAS to be beacause of the dead cory. Is this why, or am I missing something here?

Either way, what is the best plan of action? I was planning on doing a 50litre change in a few hours when my boyfriend gets home (because I am a weekling and cannot carry the water buckets ) but would this be too much considering I only changed the water two days ago?

Did you dechlorinate the replacement water? If not, the chlorine/chloramines could have damaged your beneficial bacteria colony.

 

[ghostchoir]

Yes, we're always extremely careful with the dechlorinator - so much so that we now buy in bulk so we always have quite a big collection of bottles at anytime so there's no risk of running out.

I don't overfeed them, if anything I've always been worried of doing the opposite!

I'm really not sure what went wrong.

 

[Bullrock74]

Yes, we're always extremely careful with the dechlorinator - so much so that we now buy in bulk so we always have quite a big collection of bottles at anytime so there's no risk of running out.

I don't overfeed them, if anything I've always been worried of doing the opposite!

I'm really not sure what went wrong.

Assuming you did not lose electricity for an extended period, then all I can think of is something in the tank has produced a large amount of ammonia and the bacteria that converts the nitrites to nitrates has not had a chance to catch up. I would think it is very unlikely that the death of the fish is what caused the ammonia spike because you got it out of the tank quickly. Could there be another dead fish in the tank that you haven't noticed? Are there any dead/rotting plants in the aquarium?

Whatever caused the ammonia spike, it must have happened a little while ago since the ammonia is back to zero already while the nitrites are non-zero. The good news is it sounds as if the tank is recovering and I wouldn't be surprised if soon you test for nitrites and they are back to zero. But, if the nitrites continue to climb, then you should do some water changes daily until the nitrites do come back to zero. I think most people recommend 20-25% water changes daily while either ammonia or nitrites are elevated.

 

[ghostchoir]

Nope, there's no other dead fish. I do a fish check to make sure everyone is accounted for and healthy whenever I'm looking at them (at least twice a day during feeding, but usually way way more) and I only use fake plants.

I guess I'll just do the 50l change today and then check daily to make sure things are still working or sorting themselves out correctly.