Fishless cycle, nitrate drop, cabomba?

[GraemeVW]

My 200L tank has been running for a bit over 3 week's. The cycle has been going in the right direction. It's processing ammonia, nitrites have spiked, nitrates going high (maybe 100ppm). About a week ago i did a large water change and put a large sword, 50 stems of cabomba, and some other small plants in. Readings were something like 0ppm ammonia, 5ppm nitrite, and maybe 60ppm nitrate after that.
2 days ago I dosed ammonia back up to 4ppm. Today I tested and ammonia is down to 0.5ppm, nitrite is 2ppm, but nitrate has dropped to 5ppm. I was expecting it to be back up at 80ppm+. It was 60ppm to start with and ammonia and nitrite are still being converted.

The cabomba however has probably grown 2-3" in a week.

Is that where all the nitrate has gone?
I am also dosing tnc complete.
Light is probably 1.5wpg.

I've cycled a fair few tanks and never seen nitrates drop like that, but I've also never really used many plants.

 

[Wookii]

It's likely your fast growing Cabomba are preferentially consuming much of the ammonia if you are growing a 100"-150" of stem plants a week. You don't need to add ammonia for the purposes of cycling a tank if it has already been planted, just let the plants actively grow and continue to fertilise them with the TNC, and the bacterial assemblage will naturally propagate over time.

 

[GraemeVW]

Yes, they will be taking up ammonia too, that's why I didn't plant untill the tank was processing ammonia.

I'm not growing that much cabomba in total, it's not yet growing evenly all over the tank, some gets less light and hasn't grown much at all yet. Probably grown 40" in total in a few days. The sword seems to be growing quickly too.
Oh, and there is frogbit in there too which seems to be growing and putting out long roots.

I'm just curious about the massive drop in nitrate. I've not really been too careful with the cycle, kept it dark and plant free for a few weeks untill in processed the initial 4-5ppm of ammonia I put in, then once that had gone and nitrites went up I planted, turned the light on, did a 50% water change. Then a day or so later dosed ammonia back up and left it again.
Not really doing the slow and steady, careful measuring thing. It will get there in it's own time.
I did however put some media from my pond filter in the tanks filter yesterday, purely as I'm getting a tiny bit impatient with the nitrite situ.
Diatoms are cracking on now too.

I guess the drop in nitrate just puzzled me and made me concerned I may have stalled things by letting nitrite and nitrate get too high. However, if the plants could take up that much nitrate I'll stop worrying.
I was going to water change again this weekend but the low nitrate makes me think I may as well leave it.

Plan is to wait till ammonia is 0 again and nitrite has hit 0 for the first time, then water change, then transfer my 5 red phantom tetras over as an initial test.


Edit...
If the cabomba is taking the ammonia, that makes me even more puzzled about where all the nitrate has gone!

 

[JoshP12]

The plants are turning it into … plant!!!! And you have frogbit - floaters.

I wouldn’t worry anymore about testing, once you notice those plants are growing vigorously and frogbit starts to explode, water change and toss your fish in.

You are doing a lot of well thought out steps … dark start, pond media, water changes, plants actually growing.

Trust your intuition on this one.

 

[GraemeVW]

The plants are turning it into … plant!!!!

I wouldn’t worry anymore about testing, once you notice those plants are growing vigorously, water change and toss your fish in.

You are doing a lot of well thought out steps … dark start, pond media, water changes, plants actually growing.

Trust your intuition on this one.

The only concern I have is it's only just started to drop the nitrites.
I guess it must be processing them though or I wouldn't have had sky high nitrate.

Even my hydrocotyle verticillata seems to be growing.

Just the micro sword that is currently a disaster but I think that's mainly due to low quality plants.

So, 100% water change and bung the tetras in? I've had them a couple of years in another tank and they seem unkillable anyway 😂. (Other tank suffered some heavy neglect for a while 🙁)

 

[JoshP12]

The only concern I have is it's only just started to drop the nitrites.
I guess it must be processing them though or I wouldn't have had sky high nitrate.

Even my hydrocotyle verticillata seems to be growing.

Just the micro sword that is currently a disaster but I think that's mainly due to low quality plants.

So, 100% water change and bung the tetras in? I've had them a couple of years in another tank and they seem unkillable anyway 😂. (Other tank suffered some heavy neglect for a while 🙁)

Ya stop dosing the ammonia too. Give it 2-3 days then do it IMO.

 

[Wookii]

So, 100% water change and bung the tetras in?

No - wait until you consistently measure zero ammonia and nitrites. A couple of weeks with the measures you have taken so far, should be fine at a guess.

 

[JoshP12]

No - wait until you consistently measure zero ammonia and nitrites. A couple of weeks with the measures you have taken so far, should be fine at a guess.

@GraemeVW

This is the better advice from a distance without being at the tank.

 

[Hanuman]

@GraemeVW If you add a bunch of fish now, your tank might not cope with the spike in ammonia. That's what you saw when you added more ammonia and the nitrites went up. Your tank is not yet established and bacteria can't handle sudden increase in ammonia. One way of doing this is to add fish slowly through the course of several days/weeks, or wait a few more weeks and add larger amounts of fish. I find the later more practical.

 

[GraemeVW]

Ya stop dosing the ammonia too. Give it 2-3 days then do it IMO.

In the 3 1/2 weeks it's been running, I've only dosed it twice. I just dosed it reasonably high rather than small amounts regularly.
I don't plan on adding any more.

 

[GraemeVW]

No - wait until you consistently measure zero ammonia and nitrites. A couple of weeks with the measures you have taken so far, should be fine at a guess.

That was my initial plan. Ammonia will be down to 0 by tomorrow morning, nitrite may take a little longer.

 

[GraemeVW]

@GraemeVW If you add a bunch of fish now, your tank might not cope with the spike in ammonia. That's what you saw when you added more ammonia and the nitrites went up. Your tank is not yet established and bacteria can't handle sudden increase in ammonia. One way of doing this is to add fish slowly through the course of several days/weeks, or wait a few more weeks and add larger amounts of fish. I find the later more practical.

It will be 6 months before i see it as established. Fish will go in slowly, I always do it that way.

 

[GraemeVW]

The rest of the cycle situ I'm happy with, kept fish for 30 years, including small mixed reefs.
Just never seen nitrates dissapear before!

The difference with this tank is it has plants!

 

[_Maq_]

Just never seen nitrates dissapear before!

Colorimetric tests for nitrate (all of them) are unreliable. They may be distorted by many other compounds that appear in all tanks.
I'd wait a couple more weeks. It's not only nitrogen cycle which needs to get reasonably established.

 

[GraemeVW]

Colorimetric tests for nitrate (all of them) are unreliable. They may be distorted by many other compounds that appear in all tanks.
I'd wait a couple more weeks. It's not only nitrogen cycle which needs to get reasonably established.

I have read that they are unreliable. But testing every day saw them going up and up, 50% water changes saw the level half. Then to all of a sudden drop means the test has suddenly failed or something has suddenly occurred to skew the results.
The results up till now may not ha e been accurate, but they were predictable.

 

[Ria95]

Nitrate tests will be heavily influenced / exaggerated by the presence of nitrite in the water, so wouldn't read much in the values you got from the nitrate test kit. They are not great to start with, but better saved for when you can confirm 0 nitrite with a nitrite test kit. As mentioned above that's the next step step in establishing reliable nitrification anyway.

 

[GraemeVW]

Nitrate tests will be heavily influenced / exaggerated by the presence of nitrite in the water, so wouldn't read much in the values you got from the nitrate test kit. They are not great to start with, but better saved for when you can confirm 0 nitrite with a nitrite test kit. As mentioned above that's the next step step in establishing reliable nitrification anyway.

That's interesting as the nitrate levels have basically followed the nitrite levels.

 

[JoshP12]

I have read that they are unreliable. But testing every day saw them going up and up, 50% water changes saw the level half. Then to all of a sudden drop means the test has suddenly failed or something has suddenly occurred to skew the results.
The results up till now may not ha e been accurate, but they were predictable.

That’s how I used test kits in the past as well - relative change.

I keep the old tube and compare colors, then think critically about it.

No need to squint … if it isn’t obvious, there is nothing to worry about.

 

[dw1305]

Hi all,

About a week ago i did a large water change and put a large sword, 50 stems of cabomba, and some other small plants in. 2 days ago I dosed ammonia back up to 4ppm.

Don't worry. You don't ever need to <"cycle a planted tank">, you can just plant it and wait for the plants to grow in. The reason is that "Plant / microbe" biofiltration <"is much more effective"> than "microbe only" nitrification.

I just dosed it reasonably high rather than small amounts regularly.

The issue could be that the bacteria that need heavy ammonia loadings don't actually occur in aquarium filters, but a <"whole range of other ammonia oxidising"> and <"COMAMMOX micro-organisms do">. Scientists found these new nitrifying organisms by looking for the <"DNA that codes for ammonia oxidation">. Tim Hovanec writes about this in <"Bacteria revealed">.

It's likely your fast growing Cabomba are preferentially consuming much of the ammonia if you are growing a 100"-150" of stem plants a week. You don't need to add ammonia for the purposes of cycling a tank if it has already been planted, just let the plants actively grow and continue to fertilise them with the TNC, and the bacterial assemblage will naturally propagate over time.

Same for me

I'm not growing that much cabomba in total, it's not yet growing evenly all over the tank, some gets less light and hasn't grown much at all yet. Probably grown 40" in total in a few days. The sword seems to be growing quickly too. Oh, and there is frogbit in there too which seems to be growing and putting out long roots.

I'm just curious about the massive drop in nitrate. I've not really been too careful with the cycle, kept it dark and plant free for a few weeks untill in processed the initial 4-5ppm of ammonia I put in, then once that had gone and nitrites went up I planted, turned the light on, did a 50% water change. Then a day or so later dosed ammonia back up and left it again

If the cabomba is taking the ammonia, that makes me even more puzzled about where all the nitrate has gone!

Like the others have said it is the plants, they take up all forms of fixed nitrogen. Have a look at <"Is expensive bio media worth it?">.

Just never seen nitrates dissapear before!

The difference with this tank is it has plants!

I think so, it is just that <"plant uptake is much more important"> than most aquarium literature acknowledges.

Nitrate tests will be heavily influenced / exaggerated by the presence of nitrite in the water, so wouldn't read much in the values you got from the nitrate test kit.

I'm not a great fan of <"nitrate test kits either">, I actually believe that plant leaf colour and growth is a much better method of estimating fixed nitrogen levels, to put it simply, <"the plants can't lie">. We have a thread <"The scientific background to the "Leaf Colour Chart"">.

cheers Darrel

 

[GraemeVW]

Interesting result this morning.
I added a pinch of flake last night. This morning, I hadn't emptied the test tubes and it was showing high nitrates. Seems it took 5-10 hours for the test to show.

Tested again this morning, 0.25ppm ammonia, maybe 4ppm of nitrite, and 160ppm+ of nitrate.

Not sure what was going on yesterday, did the nitrate test 3 times to check, but today it's back to how I'd have predicted the results.

I think I'll change some water as the nitrate is getting out of hand.

On the plus side, the nymphaea bulbs I planted yesterday are showing signs of growth already!