Confusion as to when 'cycling' is complete.

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Bruce Leyland-Jones

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I've known about the Nitrogen Cycle and cycling tanks for a while and have always viewed it as creating a population of beneficial bacteria, that will then be able to help manage fish waste.
I've known it to be a time-consuming process, when starting from scratch and that measuring the levels of ammonia, nitrites and nitrates in the water is an essential part of this process...with such readings indicating the progress of the cycling progress.
My preference has always been for fishless cycling, in a planted tank, so as not to stress the fish.

Note my comment about time consuming...whilst I've learned that we can now speed things up a little, by adding shop-bought, bottled bacteria, real cycling does take time to occur.
I've also always believed that, once cycled, for a tank to stay safely cycled, with the water remaining safe for fish, additions of fish to the tank needs to be done slowly, so as not to overwhelm the now-resident bacteria.

But within this forum, I've read from those considered to be experts, that once a tank is cycled, you can add all of your fish. Granted, this is usually accompanied by the caveat of water changes and continued monitoring of the water, but still...all of your intended fish can be added to a freshly cycled tank. Whilst I'll accept, albeit begrudgingly, that in some instances this can occur, I'd ask that just because we can, should we?

Another point that confused me was an insistence by another acknowledged expert was that a tank reading zero for ammonia, nitrite and nitrate must be cycled. I countered this and suggested by that statement, a bucket of tap water, with water conditioner, could then be described as 'cycled'. This was then countered by my bucket not containing fish and so it could not be described as cycled.
I have since kept fish in a bucket of fresh, conditioned, tapwater and it took many hours before I detected a trace of ammonia. Each measurement prior to this would have suggested that my bucket was 'cycled', even though it clearly wasn't.

To me, for a tank to be 'properly' cycled, it has to have achieved a state of biological balance and this balance has to be maintained over time. As soon as that balance is upset, then the cycle has been disrupted and would take careful management to be re-established.
A new tank needs to be cycled, but I'm struggling with the idea that a cycled tank is just that...cycled. As if the task of setting it up is now done and dusted.

Thoughts?
 
With fishless cycling, a cycled tank is one which can remove a 3 ppm dose of ammonia though to nitrate within 24 hours.
With fish-in cycling, a cycled tank is one which has had zero ammonia and zero nitrite for a week. But it is cycled only for the amount of fish currently in the tank.
With silent/plant cycling, a cycled tank is one which never shows a trace of ammonia or nitrite after fish are placed in the tank.


All cycling means is growing two colonies of micro-organisms* which remove ammonia and nitrite. The word 'cycling' is derived from the nitrogen cycle, though the last stage, nitrate to nitrogen gas, rarely occurs in fish tanks.
Silent/plant cycling strictly speaking isn't cycling as few bacteria grow.

Yes, there does need to be a whole host of other micro-organisms in a tank besides these two. But it's these two that stop the fast killers building up an a fish tank which is why we concentrate on them.
Your definition sounds like my definition of a mature tank.




*some of which may not be bacteria, but I use the word 'bacteria' so as not to over complicate things for new starters.
 
I've known about the Nitrogen Cycle and cycling tanks for a while and have always viewed it as creating a population of beneficial bacteria, that will then be able to help manage fish waste.
I've known it to be a time-consuming process, when starting from scratch and that measuring the levels of ammonia, nitrites and nitrates in the water is an essential part of this process...with such readings indicating the progress of the cycling progress.
My preference has always been for fishless cycling, in a planted tank, so as not to stress the fish.

Note my comment about time consuming...whilst I've learned that we can now speed things up a little, by adding shop-bought, bottled bacteria, real cycling does take time to occur.
I've also always believed that, once cycled, for a tank to stay safely cycled, with the water remaining safe for fish, additions of fish to the tank needs to be done slowly, so as not to overwhelm the now-resident bacteria.

But within this forum, I've read from those considered to be experts, that once a tank is cycled, you can add all of your fish. Granted, this is usually accompanied by the caveat of water changes and continued monitoring of the water, but still...all of your intended fish can be added to a freshly cycled tank. Whilst I'll accept, albeit begrudgingly, that in some instances this can occur, I'd ask that just because we can, should we?

Another point that confused me was an insistence by another acknowledged expert was that a tank reading zero for ammonia, nitrite and nitrate must be cycled. I countered this and suggested by that statement, a bucket of tap water, with water conditioner, could then be described as 'cycled'. This was then countered by my bucket not containing fish and so it could not be described as cycled.
I have since kept fish in a bucket of fresh, conditioned, tapwater and it took many hours before I detected a trace of ammonia. Each measurement prior to this would have suggested that my bucket was 'cycled', even though it clearly wasn't.

To me, for a tank to be 'properly' cycled, it has to have achieved a state of biological balance and this balance has to be maintained over time. As soon as that balance is upset, then the cycle has been disrupted and would take careful management to be re-established.
A new tank needs to be cycled, but I'm struggling with the idea that a cycled tank is just that...cycled. As if the task of setting it up is now done and dusted.

Thoughts?

I struggled and still do to be honest to understand.

During my recent issue with my Penguin Tetras, before they were introduced, I took API Tests for Ammonia- nitrate and nitrate - all of which were Zero also confirmed by LFS - I noted some replies on the thread put this down to the plants in the aquarium. (mature filter material also used)

So if you have a planted tank (as I understand it or not as the case may be) it was/is (again from some posts on the subject) possible will never "cycle" -

Be gentle me please - want to learn.

ATB
 
Plants can remove the need to cycle a tank. Plants remove ammonia made by fish faster than bacteria can and they don't turn it into nitrite or nitrate. But before fish can be added to a tank with plants, there must be enough plants to remove the ammonia made by all the fish added, and they must be actively growing. A tank with just a few newly planted plants may not be able to cope.

A tank which has no fish in it yet will test zero for ammonia and nitrite. In other words, the same as the water used to fill the tank. It's only after fish are put in that ammonia appears. If there are not enough plants, they won't be able take up all the ammonia made by the fish. And as there are no bacteria in a brand new tank any left over ammonia will start to build up leaving the fish keeper doing a mixture of fish-in and plant cycling.

We always recommend using fast growing plants to do a plant cycle. And waiting at least a couple of weeks after the plants are put in before getting fish so we know that the plants have established themselves.
 
I struggled and still do to be honest to understand.

During my recent issue with my Penguin Tetras, before they were introduced, I took API Tests for Ammonia- nitrate and nitrate - all of which were Zero also confirmed by LFS - I noted some replies on the thread put this down to the plants in the aquarium. (mature filter material also used)

So if you have a planted tank (as I understand it or not as the case may be) it was/is (again from some posts on the subject) possible will never "cycle" -

Be gentle me please - want to learn.

ATB
I recall your actual issue was down to the added wood. ;)
 
Plants can remove the need to cycle a tank. Plants remove ammonia made by fish faster than bacteria can and they don't turn it into nitrite or nitrate. But before fish can be added to a tank with plants, there must be enough plants to remove the ammonia made by all the fish added, and they must be actively growing. A tank with just a few newly planted plants may not be able to cope.

A tank which has no fish in it yet will test zero for ammonia and nitrite. In other words, the same as the water used to fill the tank. It's only after fish are put in that ammonia appears. If there are not enough plants, they won't be able take up all the ammonia made by the fish. And as there are no bacteria in a brand new tank any left over ammonia will start to build up leaving the fish keeper doing a mixture of fish-in and plant cycling.

We always recommend using fast growing plants to do a plant cycle. And waiting at least a couple of weeks after the plants are put in before getting fish so we know that the plants have established themselves.
Thanks - still a little confused as I used "mature filter material", and the readings were as above - Zero-Zero-Zero - my tank was not cycled ? My tests never wavered even when the fish were introduced - again be gentle please - big learning curve).

Thank you
 
Last edited:
I've known about the Nitrogen Cycle and cycling tanks for a while and have always viewed it as creating a population of beneficial bacteria, that will then be able to help manage fish waste.
I've known it to be a time-consuming process, when starting from scratch and that measuring the levels of ammonia, nitrites and nitrates in the water is an essential part of this process...with such readings indicating the progress of the cycling progress.
My preference has always been for fishless cycling, in a planted tank, so as not to stress the fish.

Note my comment about time consuming...whilst I've learned that we can now speed things up a little, by adding shop-bought, bottled bacteria, real cycling does take time to occur.
I've also always believed that, once cycled, for a tank to stay safely cycled, with the water remaining safe for fish, additions of fish to the tank needs to be done slowly, so as not to overwhelm the now-resident bacteria.

But within this forum, I've read from those considered to be experts, that once a tank is cycled, you can add all of your fish. Granted, this is usually accompanied by the caveat of water changes and continued monitoring of the water, but still...all of your intended fish can be added to a freshly cycled tank. Whilst I'll accept, albeit begrudgingly, that in some instances this can occur, I'd ask that just because we can, should we?

Another point that confused me was an insistence by another acknowledged expert was that a tank reading zero for ammonia, nitrite and nitrate must be cycled. I countered this and suggested by that statement, a bucket of tap water, with water conditioner, could then be described as 'cycled'. This was then countered by my bucket not containing fish and so it could not be described as cycled.
I have since kept fish in a bucket of fresh, conditioned, tapwater and it took many hours before I detected a trace of ammonia. Each measurement prior to this would have suggested that my bucket was 'cycled', even though it clearly wasn't.

To me, for a tank to be 'properly' cycled, it has to have achieved a state of biological balance and this balance has to be maintained over time. As soon as that balance is upset, then the cycle has been disrupted and would take careful management to be re-established.
A new tank needs to be cycled, but I'm struggling with the idea that a cycled tank is just that...cycled. As if the task of setting it up is now done and dusted.

Thoughts?
I had a tank that ran for 2 years. Bio culture added very frequently. Eventually ppl started referring to it as the bullet proof tank lol it could handle just about anything and barely can build up nitrates. Dropping in was no 2nd thought to bio load anymore. But if not I do go with dropping slowly to build up a handle on the bio load in the beginning like you mention. I like your bucket analogy 🤣
 
I struggled and still do to be honest to understand.

During my recent issue with my Penguin Tetras, before they were introduced, I took API Tests for Ammonia- nitrate and nitrate - all of which were Zero also confirmed by LFS - I noted some replies on the thread put this down to the plants in the aquarium. (mature filter material also used)

So if you have a planted tank (as I understand it or not as the case may be) it was/is (again from some posts on the subject) possible will never "cycle" -

Be gentle me please - want to learn.

ATB
No itvw
I'm picking up on the idea that whilst cycling needs to reach a level to make the tank safe for fish, it is never truly 'complete' and needs some maintenance to be maintained. ;)
yes,
I'm picking up on the idea that whilst cycling needs to reach a level to make the tank safe for fish, it is never truly 'complete' and needs some maintenance to be maintained. ;)
😜🙌🏼exactly
 
I struggled and still do to be honest to understand.

During my recent issue with my Penguin Tetras, before they were introduced, I took API Tests for Ammonia- nitrate and nitrate - all of which were Zero also confirmed by LFS - I noted some replies on the thread put this down to the plants in the aquarium. (mature filter material also used)

So if you have a planted tank (as I understand it or not as the case may be) it was/is (again from some posts on the subject) possible will never "cycle" -

Be gentle me please - want to learn.

ATB
Hmmm it can be hard to witness it lol but I’ve seen it for a slight bit…it’s just a tad bit of nitrite then it’s gone. You literally can miss it. I was lucky bc I was testing around the clock so I saw it. I often see it with half my tanks ..so if I do cycle 6-7 tanks half of them I get to see and not the others. Plants is tricky though. They all eat different ..some eat fast some eat slow. For cycling I go for the fast eaters lol
 
Thanks - still a little confused as I used "mature filter material", and the readings were as above - Zero-Zero-Zero - my tank was not cycled ? My tests never wavered even when the fish were introduced - again be gentle please - big learning curve).

Thank you
Like stealing a rock or hard sale from a cycled tank? Yes that definitely works 😂I cheat all the time rofl
 

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