# Can nitrate stall the cycle when fish-less cycling?



## TurtleShark (Feb 19, 2013)

Hi all!

I'm part of a group that really pushes fish-less cycling. 

They go through the whole 2 to 4ppm of ammonia. Test. When ammonia/nitrite drop to zero it's cycled. 

But, whenever anyone posts a picture of their API liquid test results when cycling several people jump in to claim that "your nitrate is too high. It's preventing the bacteria from converting". 

I have never heard this before. Is it just a rumor that someone started in that group that's caused the idea? Or is it actually true? In all of the fish-less cycling guides that I can find they don't mention high nitrate except at the end when you need to do a water change to bring it down. A few mention that the cycle can stall if the tank is lacking nutrients but not stall if nitrate is too high preventing conversion of nitrate. 

They consider this to happen once the nitrate test is "off the chart". I know water changes don't really hurt a fish-less cycle and I do suggest trying one for a tank that seems to have stalled. 

Any thoughts?


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## lksdrinker (Feb 12, 2014)

Nitrate is the end result of the entire process. It doesnt appear unless bacteria is consuming nitrite (and that nitrite wont appear unless bacteria is already consuming ammonia). If the nitrate reading is off the charts that tends to imply the cycle is complete. Personally if I'm trying to cycle a tank I wont bother testing for nitrate. Its irrelevant during the cycling process IMO.


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## roadmaster (Nov 5, 2009)

Cycle can stall in nitrite stage if using too much ammonia.
Might try reducing the amount of ammonia by 1/2 once nitrites appear.
If you were/are adding 4ppm ammonia ,then try 2ppm and see if things don't progress a bit quicker.


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## TurtleShark (Feb 19, 2013)

That's always been my thinking to. But time and time again I see people saying that nitrate reading that is too high is going to stall the cycle. 

And no, normally the cycle isn't stalled yet. It's just simply a person asking how soon their cycle will be done (generally after they see a nitrite spike). I always say to just keep adding ammonia and let it do its thing. A few months ago, I was getting multiple negative comments every time I would suggest a water change to help a stalled cycle. By stalled I mean that the person reported that a cycle that was once processing the full amount of ammonia every few days was no longer making any changes to ammonia/nitrite/ or nitrate. Now those same people recommend a water change for a cycle that isn't stalled because nitrate is too high. 

I was simply looking for opinions on a different place to see if maybe there was new research or something supporting nitrate stalling.


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## theatermusic87 (Jun 22, 2014)

Yes NITRATE can stall the cycle (though you need very high 100ppm+ levels), no you can not have too high a concentration of ammonia (realistically anyways)

see this thread for details. Rather a fun experiment to see just how far you could push basic biological filtration. http://www.plantedtank.net/forums/9-equipment/1045898-matrix-without-seachem.html

Basically in a nut shell you can have very little and still process a RIDICULOUSLY HUGE amount of ammonia (somewhere 50ppm+) into nitrate. though anything more than ~25ppm ammonia processed was stalling the cycle unless daily 100% water changes were performed due to the (unmeasurably high) nitrate level


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## Maryland Guppy (Dec 6, 2014)

Once NO3 API test is red you also really don't know what you have.


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## Immortal1 (Feb 18, 2015)

theatermusic87 said:


> Yes NITRATE can stall the cycle (though you need very high 100ppm+ levels), no you can not have too high a concentration of ammonia (realistically anyways)
> 
> see this thread for details. Rather a fun experiment to see just how far you could push basic biological filtration. http://www.plantedtank.net/forums/9-equipment/1045898-matrix-without-seachem.html
> 
> Basically in a nut shell you can have very little and still process a RIDICULOUSLY HUGE amount of ammonia (somewhere 50ppm+) into nitrate. though anything more than ~25ppm ammonia processed was stalling the cycle unless daily 100% water changes were performed due to the (unmeasurably high) nitrate level


LOL, I do seem to remember that thread :grin2: Kinda blew my mind when I was dumping 1/4 cup of ammonia into 10 gallons of water and the little sponge filter processed it all into Nitrate in 24 hours.


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## TurtleShark (Feb 19, 2013)

I found that test to be quite interesting. So, basically, if you fully cycle a tank to, say, 2ppm once every 24 hours it's likely that the tank can actually handle a level much higher than that. And nitrate needs to be insanely high (much over 100ppm) to actually crash the cycle. 

Now, my question is how high must nitrite be to crash a cycle? 

I guess I'll continue advising people that water changes won't hurt, but that their cycle is probably a little more stable than they think it is. It is quite amazing what our filters can do.


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## OVT (Nov 29, 2011)

theatermusic87 said:


> Yes NITRATE can stall the cycle (though you need very high 100ppm+ levels)


I cannot find much information on NO3 affecting our becteria. How does a high level of nitrate stalls the cycle?


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## Immortal1 (Feb 18, 2015)

OVT said:


> I cannot find much information on NO3 affecting our becteria. How does a high level of nitrate stalls the cycle?


I.m not exactly sure "how" it stalls the processing of ammonia, just know that it did. Somewhere in that giant thread is where I made that discovery. As for testing how much Nitrate it took, it was really hard to tell as the API Nitrate test kit was basically dark red - which could be anything from 80-160ppm or greater. Given the amount of ammonia being processed, I believe I read somewhere (and it may be in that thread) what the ratios were. And is was not a 1 to 1 to 1 ratio either. (i.e., 1ppm ammonia broke down to I believe a higher amount of Nitrite. XX ppm of Nitrite broke down to a higher amount of Nitrate.

OVT, from what I remember, during testing I would dump in lets say 20ppm ammonia and 24 hours later I had 0ppm ammonia. So then I went with 30ppm ammonia and 24 hours later the API ammonia test was off the charts. Why? So, somewhere I thought lets do a water change and see what happens. I changed 100% of the water and immediately dumped in 30ppm ammonia and 24 hours later I had 0ppm ammonia - AhHa! So I then did another 100% water change followed by 40ppm ammonia. 24 hours later I had 0ppm ammonia. Also, when the ammonia *did not* process due to high Nitrates, there was very little Nitrite per the API test. When the ammonia *did* process, there was 0ppm Nitrite.


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## mgeorges (Feb 1, 2017)

Let's say you're starting a brand new cycle, will any BB establish at that high of an ammonia concentration? Or must you have an established BB colony already to get away with that?


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## Immortal1 (Feb 18, 2015)

mgeorges said:


> Let's say you're starting a brand new cycle, will any BB establish at that high of an ammonia concentration? Or must you have an established BB colony already to get away with that?


I guess to answer your question - no. From what I have learned, you really need to start a fishless cycle out with 1-4ppm ammonia. Once the BB colony has established, then you "could" continue building it up.
Bear in mind, when most people do a fishless cycle they are doing it in the tank/aquarium they plan on using. 4ppm ammonia could be considered fairly high for any tank unless it was seriously overstocked.

Now, if you knew you were going to be setting up an 80 gallon tank in a month but only had a 10 gallon tank at the moment, then you could do as I did and build up the BB colony to meet your future needs.


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