Nitrites not going down

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.

Lize

Aquarium Advice Apprentice
Joined
Jul 26, 2024
Messages
24
Location
SA
Good morning,

I have been doing a fishless cycle for about 6 weeks now.

Each day I dosed with beneficial bacteria in a bottle, and ammonia to about 4ppm.

For the past 2 weeks the ammonia has been neutralised within 24 hours. Nitrites remain high.

Do I need to keep dosing ammonia each day for the ammonia neutralising bacteria to be kept alive? Or do I stop with the ammonia, since I feel the more ammonia I put in, the more nitrites I have?

Nitrates are also present. But my biggest concern is the nitrites that struggles to go down.

I did a 25% water change about 3 days ago and it feels that the nitrites spiked after that. Before that the ammonia neutralised in 24 hours and the nitrites to about 0.25ppm in the same 24 hours. But now after dosing ammonia the nitrites does not come down as easily.

Sand used as ‘gravel’, lots of plants, Submersible filter, bonsai tree with java moss attached at the top.

Thanks in advance for any advice!
 
The nitrite to nitrate stage usually takes longer to establish than the ammonia to nitrite stage. So what you are seeing isn't unusual.

1ppm of ammonia converts to 2.7ppm of nitrite, so those 4ppm of ammonia is actually converting to nearly 11ppm of nitrite. When the nitrite to nitrate hasn't established yet the nitrite can build up very quickly, and then when that nitrite to nitrate stage is established it can still take weeks to remove everything that's built up. Most nitrite tests only go up to 5ppm, but if you have been dosing 4ppm of ammonia every day for 6 weeks that nitrite could be up in the 100s.

You don't need to dose 4ppm of ammonia every day. You are cycled enough to stock a tank when you can cycle out 2ppm of ammonia to zero ammonia and nitrite on 24 hours. So you only need to be dosing 2ppm. And you don't need to dose daily either. Those microbes converting ammonia to nitrite aren't going to die off because you skip a day or 2. Skipping a day or 2 might give your nitrite to nitrate microbes a chance to catch up without another high amount of nitrite being added into the equation.

And personally, I like to see where my parameters are at. As said, your test kit can only detect up to 5ppm nitrite, if its above that level you have no idea how high it is. So, I would do sufficient water changes to bring nitrite down to a detectable level, dose 2ppm ammonia and see where you are 24 hours later.

Nitrite in the water causes the nitrate test to show a positive result, even when there is no nitrate. You might have nitrate, you might not. If you do have nitrate, because of the presence of nitrite the test will show a higher result than you actually have. There is no point in testing for nitrate when you have nitrite in the water because it will give a false reading.
 
Thanks Aiken!

I am going to do the water change and perhaps skip today and tomorrow to dose ammonia and see where I am at.
 
Just be aware that if say your nitrite is at 100 (it might be higher), to get it to a readable level (below 5ppm) would take in excess of a 95% water change. Or if you are doing 50% water changes it would take 5 x 50% water changes. I would do the 50% water changes, retest for nitrite after every water change, and keep doing that until you are below 5ppm. Redose 2ppm ammonia once the nitrite is readable.

Or do a 50% water change, redose a smaller amount of ammonia, say 1ppm and repeat that daily until your nitrite is readable.
 
Last edited:
Just be aware that if say your nitrite is at 100 (it might be higher), to get it to a readable level (below 5ppm) would take in excess of a 95% water change. Or if you are doing 50% water changes it would take 5 x 50% water changes. I would do the 50% water changes, retest for nitrite after every water change, and keep doing that until you are below 5ppm. Redose 2ppm ammonia once the nitrite is readable.

Or do a 50% water change, redose a smaller amount of ammonia, say 1ppm and repeat that daily until your nitrite is readable.
Hi Aiken,

Thank you for this. I was about to ask the above. I changed about 60% of the water and reading for Nitrites are still far above the 5ppm mark.

Perhaps a stupid question-but does water changes not also ‘dilute’ the beneficial bacteria? Or will it not do anything to the already established bacteria?

I am going to do 50-60% water changes until my Nitrites are below the 5ppm mark and then redose as you said above.

Thank you! Seems in this hobby that you never stop learning something new!
 

Attachments

  • IMG_0154.jpeg
    IMG_0154.jpeg
    138.5 KB · Views: 1
Those microbes that consume ammonia and nitrite are living throughout your aquarium. They mostly live on surfaces where there is a good flow of oxygenated water. So this will be on the glass your aquarium is made from, on the substrate, on your aquascape etc. But the area where these conditions mostly exist is on your filter media, in your filter. Very few of these microbes are present in the water. That's where they start out from, but as your cycle establishes they find their way onto a surface and grow and spread out from there. That's what cycling is.

So yes, a water change will dilute these microbes, but its the microbes already established elsewhere in the aquarium that are doing the job of consuming the ammonia, and new microbes will grow from these established ones.

One thing you could try to get a more accurate result for nitrite would be to take 1ml of water from your aquarium and 4ml of tapwater in your test tube and test that. If that gives you a readable test result, multiply the result by 5x. Might give you an idea how far above 5ppm your nitrite is.
 
Last edited:
Just so you can see, this is a picture of the cycling process in graph form. As you can see, the nitrite to nitrate part is longer than the ammonia to nitrite stage. 1727627144926.jpeg
So your tank is not fully cycled until your ammonia and nitrite go up then back down to zero and your nitrates are rising. A rise in nitrates alone does not mean you are fully cycled. 6 weeks is not really all that long for a full cycling to be accomplished. If you are doing a fishless cycle, I would not change water to reduce the nitrites because you need those microbes to have plenty of food ( nitrites) to reproduce which in the end, makes a stronger biological filter bed. If you want to speed up the process, add some filter material from a healthy established tank which will have the microbes present already. All they would need to do is eat and reproduce. Unfortunately, not all "Bacteria in a bottle" products really work. Since the filter material has more oxygenated water going through it, more microbes will be present in it.

Hope this helps (y)
 
Just so you can see, this is a picture of the cycling process in graph form. As you can see, the nitrite to nitrate part is longer than the ammonia to nitrite stage. View attachment 390618
So your tank is not fully cycled until your ammonia and nitrite go up then back down to zero and your nitrates are rising. A rise in nitrates alone does not mean you are fully cycled. 6 weeks is not really all that long for a full cycling to be accomplished. If you are doing a fishless cycle, I would not change water to reduce the nitrites because you need those microbes to have plenty of food ( nitrites) to reproduce which in the end, makes a stronger biological filter bed. If you want to speed up the process, add some filter material from a healthy established tank which will have the microbes present already. All they would need to do is eat and reproduce. Unfortunately, not all "Bacteria in a bottle" products really work. Since the filter material has more oxygenated water going through it, more microbes will be present in it.

Hope this helps (y)
Thanks Andy!
 
Good morning Andy and Aiken,

I hope both of you are doing well.

Just an update-after the water change yesterday I tested the Nitrites again this morning. They are at 0ppm. I did the 4ml tap water versus 1ml tank water and x 5 it came to 5ppm yesterday.

I added very little ammonia and will take the ammonia levels after it has filtered through out the tank.

Hopefully both the ammonia and nitrites will be zero within a day or two.

Thanks again for your advice!
 

Latest posts

Back
Top Bottom