10% Water Change Cased Nitrite Spike

[Ben Harper]

Hi all,

I done a 10% water change on what I belived to be my health fish tank at the weekend... The last time i checked my water (which was just over a week ago) all the readings were fine... At the weekend I did this small water change and within a hour the nitrite had spiked, but the only fish which semmed to be stuggling were my 2 large (6 inche plus) Tin Foils and a large Ruby Shark, they were swimming upside down and seemed to be breathing really fast. The other fish in the tank seemed to be ok (3 small Oscars, a common Plec, and 5 Clowns)and were chasing each other around the tank like normal. What I am struggling to understand is what caused this sudden spike in a tank which has been set up over 2 years now and why it only effected my Tin Foils and a Ruby Shark. I did a large water change to bring the Nitrite down and increaed the number of air stones in the tank. I have tested my water again last night and all the readings seem fine again....

 

[Curiosity101]

I definitely wouldn't presume the water change was at fault.

Few questions,
How often do you do water changes and how big are they on average?
Do you dechlor water before it goes in? or if you use a python or similar do you de-chlor the whole tank or just for the amount you're replacing?
What are your complete water stats right now?
What filtration do you have on the tank?
Has there been and work on the water lines supplying your house?

 

[Ben Harper]

I definitely wouldn't presume the water change was at fault.

Few questions,
How often do you do water changes and how big are they on average? I do small water changes of about 10% once a week...

Do you dechlor water before it goes in? or if you use a python or similar do you de-chlor the whole tank or just for the amount you're replacing? I add tap safe to water which I am adding to the tank.

What are your complete water stats right now? Like I said, when I tested last night they where all back to within normal range, I can not remember 100% what they were, but there was nothing alarming.

What filtration do you have on the tank? I have 2 x tetratec ex 1200 in a 550 litre tank.

Has there been and work on the water lines supplying your house? I am not aware of any work.

 

[Curiosity101]

I'd feel happier knowing the actually ppm results of the tank yesterday. Could you re-test and post the results up? Just to be sure

I think you could probably do with upping your % water change to be honest, but the tank stats will either confirm or dismiss that.

Your filtration is really quite low for a tank that size... there is a small chance not enough water is getting processed to keep the levels down. I doubt it's that... but it's a possibility.

 

[Miss Dib Dabs]

If the water company you live under are anything like mine it could have been the water. I am assuming no fish are missing and you did not clean filters or in-tank decor etc?
It is worth keeping track of what the local water company is up to and adjusting when you do your changes if need be. I've been caught a number of times over the years which probably happens about once a year on average by the local water company fiddling with water params or pipes etc. Prehaps the option if this is the case is to test water before and after a change and look for differences. If there are none then something else is the cause but at least that possiblity has been ruled out.
I might try that myself!
P.

 

[Curiosity101]

Prehaps the option if this is the case is to test water before and after a change and look for differences. If there are none then something else is the cause but at least that possiblity has been ruled out.

A fair point, definitely worth testing the tap water... although on a 10% water change if the nitrites came from the tap then the tap reading would have to have been pretty high... anything up to 5ppm I'd have thought.

 

[Ben Harper]

The filters are ment to be for a 200 - 500 litre tank and I have got 2 of them.. They turn around 2400 litre a hour which I felt would be enough concidering I have only got/had 4 x 2 inch Clown Loaches, 1 x 5 inch Clown Loach, 1 x 10 inch Plec, 2 x 6 inches Tin Foils (died weekend), 1 x 6 inch Ruby Shark (died weekend, 3 x 3 inch Tiger Oscars and a 4 x Golden Loach.

Ammonia 0ppm
Nitrate 20ppm
Nitrite 0ppm
Ph 6.7

 

[Curiosity101]

There's no need to quote what the manufacturers say they're suitable for. The rule of thumb is 5-10x turnover rate min... with 5x being ok for bare tanks with 'tidy' fish. Not big meat eating messy fish.
It's not the media capacity I have an issue with. It's the turnover rate. Even under optimum conditions the flow rate is 2400...that's without the muck and general debris plus the resistance of the filter media.

At most you could be running 4.3 x your tank capacity. I would expect that value to be more like 3 though. And 3 x your tanks capacity isn't great for fish that are as big bodied and as messy as they will be at feeding time.

Did the spike co-incide with them having been fed?

And what level did the nitrites go up to?

 

[Ben Harper]

If the water company you live under are anything like mine it could have been the water. I am assuming no fish are missing and you did not clean filters or in-tank decor etc?
It is worth keeping track of what the local water company is up to and adjusting when you do your changes if need be. I've been caught a number of times over the years which probably happens about once a year on average by the local water company fiddling with water params or pipes etc. Prehaps the option if this is the case is to test water before and after a change and look for differences. If there are none then something else is the cause but at least that possiblity has been ruled out.
I might try that myself!
P.

There are no fish missing, just lost the 3. I did not touch either of the filters or any thing inside the tank, just drain down 10% of the water and replaced it

 

[Ben Harper]

There's no need to quote what the manufacturers say they're suitable for. The rule of thumb is 5-10x turnover rate min... with 5x being ok for bare tanks with 'tidy' fish. Not big meat eating messy fish.
It's not the media capacity I have an issue with. It's the turnover rate. Even under optimum conditions the flow rate is 2400...that's without the muck and general debris plus the resistance of the filter media.

At most you could be running 4.3 x your tank capacity. I would expect that value to be more like 3 though. And 3 x your tanks capacity isn't great for fish that are as big bodied and as messy as they will be at feeding time.

Did the spike co-incide with them having been fed? No, I do not tend to feed them on the day I do a water change...

And what level did the nitrites go up to? It went up about 20ppm, it was hard to tell because the colour was beyond the test kits colour chart..

 

[Curiosity101]

The nitrItes went up to 20ppm?

 

[Ben Harper]

The nitrItes went up to 20ppm?

It was hard to tell as I said it went a realy dark purple colour and the colour chart only went up to 20ppm

The nitrItes went up to 20ppm?

It was hard to tell as I said it went a realy dark purple colour and the colour chart only went up to 20ppm

Sorry my mistake my test kit only goes up to 5.00ppm so the levels were higher then that...

 

[Curiosity101]

So what did you do once you measured these levels? I can't belive for one second that 1 hour after the water change the nitrites had sky rocketed from 0 to over 5ppm.

That's practically impossible. More likely the problem was present before this and the effects just happened to be visible after the water change.

Is there anything you did over the few days before the spike? Any power cuts? Anyone fed the fish other than you? Turn the filters off and forget to put them back on?

Hmm, not sure what else I can think of

Edit to add: Also another reason I don't think it was the water bringing the nitrites in is that you'd have needed a reading of 50ppm of nitrites or very very very high levels of ammonia to give that sorta reaction.

 

[Ben Harper]

So what did you do once you measured these levels? I can't belive for one second that 1 hour after the water change the nitrites had sky rocketed from 0 to over 5ppm.

That's practically impossible. More likely the problem was present before this and the effects just happened to be visible after the water change.

Is there anything you did over the few days before the spike? Any power cuts? Anyone fed the fish other than you? Turn the filters off and forget to put them back on?

Hmm, not sure what else I can think of

Edit to add: Also another reason I don't think it was the water bringing the nitrites in is that you'd have needed a reading of 50ppm of nitrites or very very very high levels of ammonia to give that sorta reaction.

I am not saying it went from 0 to very high in an hour. The last time i checked my water levels was just over a week before this spike... There may well have been a problem starting before I carried out this water change, but all the fish looked fine.

I am the only person who feeds the fish as my partner hates fish and she would not go anywhere near them. We have had a number of small power cuts over the last few weeks, but they are not lasting more than hour each time.



The Nitrites readings were above 5ppm not 20ppm like I said earlier and if they went really high why would it only effect my Tin Foils and a Ruby Shark and have no effect on my other fish?

Once I noticed these fish struggling and tested the water I did a large water change (30-40%) and add some aquariumn salt.

 

[Curiosity101]

I'm not saying you were saying it went from 0-5ppm in an hour. But in the first few posts you implied it was the result of the water change. I'm just saying that it's almost definitely not the water change that caused this. There must be some underlying issue.

Have your filters both definitely come back on after each power cut?

And they wont have only affected your tin foils and ruby shark. It just affected them quickest and most extremely. I would expect some damage to have been done to the other fish depending on how long they were exposed.

As I said... what did you do after you read the test results? And when did the nitrites hit 0 again?