I was almost at the end... Nitrites came back!

[MajorGFX]

Hi guys,

I am not a novice fish keeper but its been a few years since i kept Tropical fish.

About 3 months ago I purchased a 350L aquarium and started doing a Fishless cycle.

I followed this guide:

http://www.aquariumadvice.com/forum...guide-and-faq-to-fishless-cycling-148283.html

And it all went 'By the book' if you like until the last step! Now I am stuck!

Aquarium Details

350L Corner Tank
External UV Filter
Internal Fluval U4
Artificial Plants
Handful of Live Plants
Sand Substrate
No fish - Small amount of Snail infestation

I started a fishless cycle on my 350 litre tank 8 weeks ago, everything went as planned and last week I could turn 5ppm of ammonia into 0 ammonia 0 nitrite and 10 ammonia within about 8 hours. So i figured I had a very strong bio filter going on...

I did the last stage of the guide, a 90% water change just before I went to add fish and now I have nitrites off the chart! Why?!

I tested my Tap Water and its free from any Nitrites, Nitrates.

Ammonia is 0, Nitrites off the chart and nitrates 10. Ph is 7.6.

Why has Nitrites come back when I could turn it to 0 over night before?

I am assuming the large water change effected it somehow?

Any help would be hugely appreciated.

 

[Delapool]

Only thing I can think of is if you checked for ammonia in tap?

Has ph or temp changed suddenly in the tank?

 

[MajorGFX]

Only thing I can think of is if you checked for ammonia in tap?

Has ph or temp changed suddenly in the tank?

Tap Water is fine with 0 readings.

It was only when I did the 90% water change and added 1PPM of ammonia that it spiked...

I have been told by another forum that I used too much Ammonia and it has stalled.

 

[tnfinfan]

Weird! You haven't added fish yet, I presume? I'd change the water again and see what happens. The only thing I can think of is that your sand had pockets and the water change stirred it up.

Wait, you did have a nitrite spike before, right?

 

[MajorGFX]

Weird! You haven't added fish yet, I presume? I'd change the water again and see what happens. The only thing I can think of is that your sand had pockets and the water change stirred it up.

Wait, you did have a nitrite spike before, right?

I had a Nitrite Spike for about 10 days, while Ammonia was going to 0 Nitrites stayed up for 10 days. Then it went down to 0 overnight. I tested it for 5 days after and it kept going back to 0 when I added 4 PPM of ammonia.

Then I did the water change and Nitrite went back off the chart.

No fish at all!

PS - Shall I stir the sand up? I will suck snails out of the tank too while changing the water.

 

[Delapool]

Was this the first water change done?

 

[tnfinfan]

That's what I'd do. Stir the sand, change the water again, and retest. Just in case.

There seem to be two lines of thinking: never, ever disturb the lower, anaerobic layer of sand or disturb it often so it doesn't accumulate nasty gases. With no fish to harm, I'd disturb the heck out of it and see if the problem vanishes after your water change. I just cannot imagine where else it could have come from and I suspect you disturbed the sand more than usual with the giant water change.

 

[MajorGFX]

That's what I'd do. Stir the sand, change the water again, and retest. Just in case.

There seem to be two lines of thinking: never, ever disturb the lower, anaerobic layer of sand or disturb it often so it doesn't accumulate nasty gases. With no fish to harm, I'd disturb the heck out of it and see if the problem vanishes after your water change. I just cannot imagine where else it could have come from and I suspect you disturbed the sand more than usual with the giant water change.

The sand is only 3 months old, and there has been no waste from fish because there isn't any. But I will do this just to put my mind at rest.

The water change was done 3 days ago.

Tests today show Nitrite off the chart.

 

[threnjen]

Did you use a dechlorinator when you did the water change?

 

[Delapool]

Did you use a dechlorinator when you did the water change?

I'm also puzzled on where the nitrate is going Threnjen if this is basically first water change. I thought nitrates is off the charts at the end due to all the ammonia being converted unless I'm missing something?

[FONT=&quot]1 [FONT=&quot]ppm[/FONT] ammonia --> 2.7 [FONT=&quot]ppm[/FONT] nitrite --> 3.6 [FONT=&quot]ppm[/FONT] nitrate.[/FONT]

 

[threnjen]

Well he did a really really large water change, so probably took most of them out, Says it's 10 nitrates right now with nitrites high. That seems plausible to me as a nitrates number.

I think you just misread (OR I did and I'm the one in the wrong) but I think he was saying nitrates at 10 is his number after the water change

 

[Delapool]

Could be OP?

 

[MajorGFX]

Hello again.

It was the Nitrites that were my concern.

Basically Nitrites got to a stage where they were 0, but they came back after a large water change.

Here is an update:

I did a 95% water change and did a test straight after (about an hour) just out of curiosity and Nitrites were still off the chart? Couldn't understand why when I change nearly all the water.

I left it overnight and Nitrites went down to 0.5PPM by the morning.

I dosed up 2PPm of Ammonia and 24 hours later Ammonia 0, Nitrites more than 5PPM, Nitrates 40PPM.

I think I am still cycling... Nitrites have been off the chart for 3 weeks now.

 

[MajorGFX]

Could be OP?

Sorry, it was about the 3rd water change I have done. Nitrates at one point was over 160PPM.

I do have some live plants in there. Nitrates is now up to 40PPM as the above post will outline

 

[Delapool]

Thanks - makes more sense on nitrates (I must of got confused pre-morning coffee)...

 

[threnjen]

OK. Looks like things are back on track but I agree that you're still cycling. You are probably pretty close, though

 

[MajorGFX]

OK. Looks like things are back on track but I agree that you're still cycling. You are probably pretty close, though

Thanks guys and girls

I will keep you all updated.

 

[tnfinfan]

Um, call me crazy but I'd stop dosing ammonia, let the nitrite drop to zero, and do a gradual stocking. You clearly have enough bacteria present to handle a moderate amount of ammonia. If you stock gradually, the bacteria will keep up. JMO.

 

[MajorGFX]

Um, call me crazy but I'd stop dosing ammonia, let the nitrite drop to zero, and do a gradual stocking. You clearly have enough bacteria present to handle a moderate amount of ammonia. If you stock gradually, the bacteria will keep up. JMO.

I am just going to wait it out, hopefully the Nitrite will go to 0 overnight,

Sick of seeing Purple now!!!

 

[MajorGFX]

Still adding 2PPM of Ammonia every 24 hours.

Nitrites still over 5PPM and Nitrates at 40PPM.

No change still, been 4 weeks + with Nitrites now