Curious case of no Nitrates? Expert opinion needed.

[PARAGUAY]

I just rely for macros, every time i add macros in the water, sensitive plants get stunted

If it works that's all that counts🙂

 

[MichaelJ]

Maybe l read too much, but have read somewhere relying on fish food for nutrients is very unreliable

Relying on fish and food waster is perilous for sure. There might be situations where you can get away with it long term, say in a fairly well stocked tank and really slow growing hardy plants such as Anubias, infrequent water changes etc. Back in my South American Cichlid days I didn't add any fertilizers for the few plants I would pop in here and there. I never really had nutrient issues as most plants would be torn apart and shredded to pieces before it got to that

Cheers,
Michael

 

[_Maq_]

I believe you are currently conducting experiments in this field. Any results yet?

Yes. Results I have but pretty unexpected ones. I can observe virtually nothing. The plants in three tanks seem to suffer no deficiency after two months deprived of any magnesium, calcium, and potassium, respectively.
This - and some similar observations - has led me to an opinion which I've already mentioned in another thread . In time, the substrate develops in a fairly strong reservoir of nutrients. No other explanation comes to my mind.

I don't want to add nitrates either because every time i did, i got stunted growth on sensitive plants.

This is very interesting observation. Perplexing, I have no explanation.

I don't think holes in leaves and potassium are as related as we've been told in the past.

I believe the same. Beside that, I've studied some agronomy literature and nobody ever mentioned holes in the leaves in connection with potassium. Magnesium, maybe.

But I believe the fish food products iron ratio didn't agree with marcher

I rather think that it's not iron deficient. The problem is the time before iron passes through all those transformations which make it available for plants. In certain cases (high pH/alkalinity, some species) it may take an eternity.

 

[_Maq_]

I don't want to add nitrates either because every time i did, i got stunted growth on sensitive plants.

This is very interesting observation. Perplexing, I have no explanation.

After a while, I think I've got something like a hypothesis.
I remember that @dw1305 once commented as 'strange' when I mentioned that I haven't faced nitrogen deficiency for a long time. I have formulated a theory that - apart from light and CO2 - the growth of our plants is controlled by nitrogen. Plants grow as quickly as nitrogen availability permits. And since I fully control mineralization of my water and follow Marschner's ratios, nitrogen is never in relative excess nor deficiency. Sometimes I can observe deficiency of iron or phosphorus. That's easy to explain due to their particular behaviour. But for the rest, my fertilizing pattern works without issues.
Back to @eminor 's case: Some nutrients, possibly some micros, are present in amounts which suffice just for slow growth and nothing more. If adding nitrogen, plants "want" to grow faster - because nitrogen controls the growth - but those scarce nutrients cause that stunting develops.
What do you think?

 

[eminor]

After a while, I think I've got something like a hypothesis.
I remember that @dw1305 once commented as 'strange' when I mentioned that I haven't faced nitrogen deficiency for a long time. I have formulated a theory that - apart from light and CO2 - the growth of our plants is controlled by nitrogen. Plants grow as quickly as nitrogen availability permits. And since I fully control mineralization of my water and follow Marschner's ratios, nitrogen is never in relative excess nor deficiency. Sometimes I can observe deficiency of iron or phosphorus. That's easy to explain due to their particular behaviour. But for the rest, my fertilizing pattern works without issues.
Back to @eminor 's case: Some nutrients, possibly some micros, are present in amounts which suffice just for slow growth and nothing more. If adding nitrogen, plants "want" to grow faster - because nitrogen controls the growth - but those scarce nutrients cause that stunting develops.
What do you think?

So while increasing macro, i should also increase micros to avoid those stunted growth problems?

 

[Wookii]

After a while, I think I've got something like a hypothesis.
I remember that @dw1305 once commented as 'strange' when I mentioned that I haven't faced nitrogen deficiency for a long time. I have formulated a theory that - apart from light and CO2 - the growth of our plants is controlled by nitrogen. Plants grow as quickly as nitrogen availability permits. And since I fully control mineralization of my water and follow Marschner's ratios, nitrogen is never in relative excess nor deficiency. Sometimes I can observe deficiency of iron or phosphorus. That's easy to explain due to their particular behaviour. But for the rest, my fertilizing pattern works without issues.
Back to @eminor 's case: Some nutrients, possibly some micros, are present in amounts which suffice just for slow growth and nothing more. If adding nitrogen, plants "want" to grow faster - because nitrogen controls the growth - but those scarce nutrients cause that stunting develops.
What do you think?

You know more about this stuff than I ever will @_Maq_ but I think in practical terms growth is controlled by whatever is the most limiting factor. I have found that restricting nitrogen has a more obvious physical effect on some plants. If I want to control growth, I would tend to limit phosphorus as that seems to minimise the physical degradation of the plants whilst slowing the plant growth. How do you normally detect phosphorus deficiency?

 

[_Maq_]

I think in practical terms growth is controlled by whatever is the most limiting factor.

That is what theory says. In low-tech and with simple lighting (I don't tend to toy with lighting very much), light and CO2 are more or less constant. Both of them are definitely limiting the growth. So, if things were so simple, if one factor is limiting and therefore the others are in relative abundance, no issues with nutrients could ever occur. Yet we know imbalances in nutrition happen.
In fact, I've read some scientific papers which assessed that the real working of Liebig's law is not that simple. On the other hand, I fully admit that my hypothesis of nitrogen controlled growth is hardly directly supported by scientific sources. It just fits well with my personal observations.

How do you normally detect phosphorus deficiency?

It's not easy, and I've been fooled several times unless I've got to know my plants a bit better. Slower growth, tinier leaves, up to a complete cessation of growth and later death. Algae disappear. I've never observed in aquarium that "dark green leaves" feature which is often mentioned in literature.

 

[dw1305]

Hi all,

Some nutrients, possibly some micros, are present in amounts which suffice just for slow growth and nothing more. If adding nitrogen, plants "want" to grow faster - because nitrogen controls the growth - but those scarce nutrients cause that stunting develops.
What do you think?

I think it is a reasonable hypothesis.

terms growth is controlled by whatever is the most limiting factor.

Nitrogen (N) is the nutrient where you can get <"instant greening">. As a resource fixed nitrogen is <"patchily available"> to organisms and I think that they are pretty good at <"both acquiring"> and stockpiling it.

The difference in nitrogen requirement between a plant like an <"Amazonian Water lily"> (Victoria amazonica) and Utricularia graminifolia (or <"Bolbitis heudelotii ">) is going to be several orders of magnitude, so I'm not sure that there is a "one size fits all" answer.

If I want to control growth, I would tend to limit phosphorus as that seems to minimise the physical degradation of the plants whilst slowing the plant growth. How do you normally detect phosphorus deficiency?

<"Work on eutrophication"> in aquatic habitats definitely suggests that phosphorus (P) (as orthophosphate PO4---) is the key player (I'll add in @Dr. White).

However, there is a complicating factor because <"phosphorus is often unavailable"> and plants have developed a <"whole range of strategies"> to make "the unavailable", <"available">.

How do you normally detect phosphorus deficiency?

It's not easy, and I've been fooled several times unless I've got to know my plants a bit better

That is the problem, <"purpling"> and pale older leaves?

Cheers Darrel

 

[barbus1]

I feel your pain every time l think l got rid it's back, then it's a case of getting the salvinia free to put back. Looks nice in the barrell pond and removing once a week

My kids would literally love that!

As for the duckweed, I went through the process of removing it from the tank in the image below about a month ago. I literally removed every visible trace of it, even removing the last tiny pieces with tweezers.

A month later, this:

View attachment 208377

I’ve gone to extreme lengths to try and prevent it’s transfer to the new tank, but every now and then the sneakiest little b@$t@rd bit of it will suddenly pop up from under a piece of Frogbit, cackling manically at me like a power hungry megalomaniac:

View attachment 208378

Melanothenias love duckweed, so we have to breed it separately

 

[dw1305]

Hi all,
Welcome to UKAPS

Melanothenias love duckweed, so we have to breed it separately

It gets a mention here as a food for Rainbow fish <"My Favourite Australian Rainbows">.

I think quite a <"lot of fish eat Duckweed">, (Lemna minor), it is high in protein etc.

cheers Darrel