Linkandnavi

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After a little help here, as I'm non-plussed. I'm mid-fishless cycle with a 450l (120 us gallon) tank and my nitrite readings are making no sense to me.

I started with adding Dr Tim's ammonia a couple of weeks ago, plus "one and only" bacteria. I know there are mixed views on whether it does anything, but figured nothing to lose and I've had seemingly good results with it in other tanks.

I followed the dosing instructions for the ammonia on the bottle, which should have been for 2ppm. Half an hour later I tested, and it was reading about 8ppm. I understand there have been some issues with the new concentration Dr Tim's ammonia being labelled with the old concentration instructions so figure this may be one such problem.

Anyway, I left it. Over the course of the last couple of weeks, that's gradually come down, to 0.5 on the 23rd, almost zero on the 24th and zero on the 25th.

Since the 25th, i.e. the last couple of days, it has remained zero, as you would expect without adding any further source.

Nitrite of course went up over this time. Because of that high dosing of ammonia, it kept going up and up and then off the charts. Knowing that too high nitrite levels can stall the cycle, I did some water changes. Over the course of two days I did three 50% water changes and then a 75% water change, which eventually lowered my levels yesterday morning to 2ppm nitrite. God knows how high it must have been to take that much changing to get it readable.

Anyway, yesterday was 2ppm nitrite and ammonia of course on zero. Today nitrites have risen to 4ppm.

How is that possible without a source of ammonia to convert from? I've been using both an API test kit and NT Labs test kit simultaneously (I wanted the assurance given the accidental high dosing of ammonia at the start) and they have both been showing the same, so it's not a kit issue.

Ammonia has been zero for a couple of days, so in another couple of days it will need a top up to keep those bacteria going, but with nitrites somehow going up not down, they'll only get worse?

Thanks.
 
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Linkandnavi

Linkandnavi

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I'm wondering if I've managed to answer my own question here but posting in case anyone has any views.

Here in London ammonia we have Chloramine in our water supply, rather than just Chlorine (i.e. it is binding of chlorine and ammonia). A dechlorinater breaks down the chlorine part but does not break down the ammonia. A treatment like Seachem Prime binds that ammonia into ammonium rendering it temporarily harmless to fish (irrelevant during my fishless cycle) but does not break down the ammonia that is left. That's the job of the nitrifying bacteria, as it would be for any other ammonia in a cycled tank.

So I'm thinking this is the potential source of my nitrite levels creeping upwards after my water changes during my fishless cycle despite not adding any more chlorine. The dechlorinator is breaking down the chloramine leaving ammonia, which is then being converted to nitrite even without knowingly adding any ammonia source. That in turn is resulting in a slow rise, rather than reduction in nitrite, as the nitrite eating bacteria aren't fully developed yet.

That's all I can think of by way of explanation right now, but struggling to work out what that would mean in terms of adding a snack dose of ammonia at this point. I'm inclined to just leave it and wait, presuming the ammonia eating bacteria will hang on in there long enough.
 

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