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Slow and limited growth VS deficiency

Alexv95

New Member
Joined
11 Sep 2020
Messages
18
Location
France
Hello,

I have a question about aquarium environment, not I new topic about lean vs rich dosing, but I would like to understand why in some cases (the majority), if the fertilization is inadequate, plants will show deficiencies (and we will get algae) while in others, we will be able to get a limited growth of the plants, which could be (very) slow but in perfect health (without algae).

The first case is very common, an aquarium where fertilization is insufficient, or often when the CO2 is not optimal, or with an incorrect water flow ... This results in unhealthy plants, with often visible deficiencies (and most often with algae). What's interesting here is that the plants can show deficiency (I guess because of an element not present in sufficient quantity to cover their needs), but they still continue to grow, sometimes even quickly. The deficiency is clearly visible but the missing nutrient does not always seem to highly affect its growth rate, or at least does not block the growth of the plant.

On the opposit, I took a specific tank as exemple, from a french forum where I often discuss. Here is the tank :
1556899110-img-1588.jpg

With the topic here (in french) : Aquascape Optiwhite 90x45x45

In this tank, the plants are mostly healthy (in my opinion, at least much better than some tanks showing deficiencies with a growing speed which remains significant), we do not get visible algae and plant growth is severely limited. For illustration here is the tank 1 month later without any trim :
1559503494-img-1633.jpg

Look pretty similar I think.

For the analysis :
The tank is 90x45x45 cm (35"x18"x18") 180 L (48 gal)
Light : Chihiros A901 plus, 100% intensity, 8 hours/day, pretty close to the surface. According to the data here, I think the PAR value should be arround 100 at the substrate level, maybe a little bit more.
CO2 : 2 bubbles/sec, cheap diffuser, under the filter outlet (I think he loses many bubbles), drop checker < green (dark green or blue), no pH analysis, I think we can consider the diffusion as low / poor.
Water changes : 20 % per week
Soil : ADA aquasoil 1 year old
Fert : nothing for the first year. After 1 year, he started to fertilize, not because he identified deficiencies but because the plants were growing too slowly to his taste. Then he added daily (but he said he often forgot) easy life products :
1.5ml nitro = 1 ppm NO3
1ml fosfo = 0.03 ppm PO4
1ml ferro = 0.07 ppm Fe (not daily)
1ml carbo
1ml profito = 0.016 ppm Fe
1ml potassium = 0.27 ppm K (not daily)
Flow : pretty strong eheim filter on paper but from what I saw on these videos, very little movement in the plants and almost no surface ripple, so low flow I guess.

Everything seems low in comparison to what we can see on other tanks which could present deficiency issues.

My question is: according to you, how an aquarium like this one will succeed in having a very slow growth of plants, very close to stop growing completely, but without deficiency, whereas in other tanks, plants can show deficiencies while continuing to grow?
The Liebig law talks about the scarcest resource as limiting factor but the line between limitation of growth and deficiency is no longer very clear to me.

And then, how to create a such environment where fert would only regulate plants growth, without deficiency issue (and algae) in parallel?

Thank you !
 
I've had the same question for some time and you stated it very clearly, thanks! I'll follow this thread to maybe see the light
I started a holding tank a month or two ago, with prodibio soil and an A301. No ferts, no CO2. And all my plants in it grow slowly but healthy, with my H'ra even showing more reds than in my high tech tank.

Envoyé de mon KB2003 en utilisant Tapatalk
 
I have a question about aquarium environment, not I new topic about lean vs rich dosing, but I would like to understand why in some cases (the majority), if the fertilization is inadequate, plants will show deficiencies (and we will get algae) while in others, we will be able to get a limited growth of the plants, which could be (very) slow but in perfect health (without algae).
Hello,
It's very difficult to compare different tanks as no hobbyist is in complete control of all the variables. People who are reporting success or failure often misrepresent the situation by inadvertently omitting certain details which are critical to understanding what is happening in the tank. The most important detail is the PAR, which governs everything else.
In the Original Post there is plenty of data, but the data has to be interpreted correctly. I'm not sure about the reported PAR, and this needs clarification.
In the linked post containing PAR data for various fixtures it's unclear exactly which fixture data is applicable. The OP mentions"
The tank is 90x45x45 cm (35"x18"x18") 180 L (48 gal)
Light : Chihiros A901 plus, 100% intensity, 8 hours/day, pretty close to the surface.
So the fixture should be approximately 90cm but I do not see a 90cm fixture in the linked thread.
There is a table for
Single Chihiro Serie A. 65W in the 120cm length PAR at 40cm= 64 micromoles
Two Chihiro Serie A. 65W in the 120cm length PAR at 40cm=110 micromoles
Single (?) Chihiros RGB 50W in the 60cm length PAR at 40cm=47 micromoles
So the questions are:
How many Chihiros A901 are powering the tank shown?
What is the wattage of this lamp?
On what basis does the OP conclude that the PAR value:
should be arround 100 at the substrate level, maybe a little bit more.

The next question is regarding the substrate.
Soil : ADA aquasoil 1 year old
Fert : nothing for the first year. After 1 year, he started to fertilize, not because he identified deficiencies but because the plants were growing too slowly to his taste. Then he added daily (but he said he often forgot) easy life products :
ADA Aquasoil contains 100 times the EI suggested nutrient concentration, so there would not have been any need to add fertilizer.

Next is CO2:
CO2 : 2 bubbles/sec, cheap diffuser, under the filter outlet (I think he loses many bubbles), drop checker < green (dark green or blue), no pH analysis, I think we can consider the diffusion as low / poor.
OK, fair assessment. We often see that by moving the gas under the filter intake this improves the dissolution of the gas.
1ml carbo
OK, well, Carbo=CO2 so one can get away with a dark green DC because the tank is being supplemented with Carbo which has no effect on the DC color, but has an effect on CO2 assimilation by the plant.

We also must clarify what kind of water is being added to the tank during the water change. Is RO water being added or is it tap water added? If tap water is being added what is the water analysis?

Flow : pretty strong eheim filter on paper but from what I saw on these videos, very little movement in the plants and almost no surface ripple, so low flow I guess.
Why would that be the default guess? There is no surface ripple because the pipe is below the surface and is pointed straight ahead. What does it say on paper exactly?

Everything seems low in comparison to what we can see on other tanks which could present deficiency issues.

My question is: according to you, how an aquarium like this one will succeed in having a very slow growth of plants, very close to stop growing completely, but without deficiency, whereas in other tanks, plants can show deficiencies while continuing to grow?
There is only a superficial relationship between growth rate and plant health. This is a mistake that many people make because they assume the opposite. Plants can grow very quickly if the lighting is very high and they will exhibit deficiency because all the products necessary for health are not present in enough abundance. CO2 and nutrients are required for plant health.

The conditions described for this tank indicates that the lighting perhaps was not as high as supposed, which can easily explain the slow growth and if that is the case, then the demand for nutrients and CO2 was also not as high as expected, whereas nutrients were present in abundance and CO2 was being supplemented via gas and liquid.

Again, these are merely guesses based on what we know about plant growth and what data seems missing or inconsistent in the description.

Cheers,
 
Hi,

Having read the original forum post that you reference I think most things can be explained.
I'd agree the rate of stem growth isn't super fast, but there is growth, and the original poster mentions on several occasions that trimming is being done.

Admittedly I've had to use Google translate to read the French post, but from what I can gather the scape pictured is at least in part a re scape, I can't determine how long the stems have been planted but the carpet was only 3 weeks old in this pic from the 10th April.

1554912993-img-1544.jpg

If we then look at a picture posted the following day you can see the rotala green has had a heavy trim.
1555001941-img-1552.jpg

Fast forward to the 3rd May and we see quite a bit of growth. (I think this is the first picture you showed)
1556899110-img-1588.jpg

And finally the 2nd picture you show from the 2nd June. I've quoted the op's comment that accompanied this pic.
"Few changes in 1 month. I did a big pruning 3-4 weeks ago, mowed the grass to even out the height a bit, transplanted the pogostemon erectus to make a second grove on the right and that's about it."
1559503494-img-1633.jpg


So we can see that pruning is taking place and if we look at the pictures from 11th April to 2nd June, we can clearly see a good bit of growth.

Regards nutrients, yes the op is a bit haphazard with dosing, sometimes adding more, sometimes adding less, and sometimes forgetting to dose at all, and always on the lean side.
However 20% of the water is replaced every week with re mineralised ro, the product used is called gh+, I don't know what that product contains or how much is used, but suspect it contains calcium, magnesium and possibly potassium.
There's also a fairly decent fish stock of 40 x-ray tetra and 8 ottolincus, along with the food they're given could this be supplying some of the nutrients seemingly lacking?

Hope this a least answers some of your questions.
 
After reading about these set-ups and dosing regimes, I can't see any particular evidence that a lack of any nutrient is inhibiting growth.

Fish food and and the ADA substrate could contain all of the nutrients needed, the higher the light intensty and the more CO2 provided, the less likely that would be the case, but it's still possible. "Lean" (to me, this just means anything less than EI levels of fertilisation) dosing doesnt actually mean limited nutrients in every situation. As Clive mentions, there are really too many variables to consider here! Different species of plants, different growth patterns (some species being shaded more), the light unit itself not providing the expected PAR...etc.

Plants can grow very quickly and still show deficency signs, or be growing more slowly than expected without nutrient limitation for multiple reasons. Depends of the species of plant, also what other plants and organisms they are growing with. Even the effects of allelopathy, of presence/absence or a particular bacteria/virus could theoretically cause one species of plant to grow at a slower rate than it normally would, which could reduce nutrient demands and prevent deficencies. One species pesent might prefer higher or lower temperatues too, and simply changing the temperatue could change the entire balance of the tank, or not. The higher the number of different species of organisms you are mixing in the same environment, the more complex these interactions become.

Personally I also think it's likely the OP on the French forum is overestimating the light input to the tank, but they dont have to be, there's so much to consider that really there is no way of knowing for sure. The only advantage of lean dosing IMO is saving money on fertiliser, purposely limiting plant growth to reduce maintencnce, or maybe if you are specifically using plants to lower NO3 for a super-delicate river fish species or something. In those situations, you can just trial and error different plant species until you find one that grows well with no visible deficencies in your particular set-up.
 
Last edited:
The plants in my window sill shrimp bowl have achieved near zero growth rate but healthy. It receives direct sunlight of 200 - 300 PAR in the afternoon but due to CO2 limitation, even stem plants grow at snail pace. The estimated CO2 is depleted to 0.1 ppm at peak sunlight. There is no sign of nutrient deficiency of any sort as it receives secondary dosing from replacement water off my high tech tank in weekly water change. But there are green thread algae ( cladophorus and spirogyra) associated with heathy eco system I have to remove by hand periodically as I don’t want to use chemical.
 
Hello,

Thank you all for your answers.
I try to give more details with what I know :

In the Original Post there is plenty of data, but the data has to be interpreted correctly. I'm not sure about the reported PAR, and this needs clarification.
In the linked post containing PAR data for various fixtures it's unclear exactly which fixture data is applicable. The OP mentions"

So the fixture should be approximately 90cm but I do not see a 90cm fixture in the linked thread.
There is a table for
Single Chihiro Serie A. 65W in the 120cm length PAR at 40cm= 64 micromoles
Two Chihiro Serie A. 65W in the 120cm length PAR at 40cm=110 micromoles
Single (?) Chihiros RGB 50W in the 60cm length PAR at 40cm=47 micromoles
So the questions are:
How many Chihiros A901 are powering the tank shown?
What is the wattage of this lamp?
I completely agree, OP does not have a PAR meter and this is an estimate that only binds me, I could be wrong.
From the linked thread, two Chihiros Serie A. 65W in the 120cm length PAR at 40cm=132 micromoles (I didn't keep the value with Apogee Underwater factor correction because the measurements were taken out of the water, but maybe I should).
OP has a Chihiro Serie A. 901 plus, 95 W, 1 unit, which is 26 % less powerful than the two Chihiros Serie A. 65W in the 120cm length.
(As an aside, I own a PAR meter (seneye reef), for the different ramps I had the opportunity to test, I found similar PAR values as elsewhere, but for chihiros A it's a different story, for the only feature I have (chihiros A 50 cm - 33 W) I measured a PAR of 100 micromoles at 40 cm).
I agree that there is a lot of uncertainty in this estimate, but I also looked at the plants : dense carpet, bushy stem plants (while CO2 seems poor) and a nice red on the rotala h'ra which I think refers to a relatively strong light. But if we can obtain the same shape with low light, I want the receipe !

ADA Aquasoil contains 100 times the EI suggested nutrient concentration, so there would not have been any need to add fertilizer.
I'm not sure to understand this sentence. 100 times the weekly dosage of EI ? But the availability of elements is not the same as it is in the soil? If not I guess Tom Barr using aquasoil would not need to fertilize in parallel as he does? I have recently rebuilt my tank, before the change I had an old aquasoil (5 years) with EI dosing, the plants grew very fast. The new version got a new aquasoil and now a lean dosing, I have to say that the plants are growing much slower now despite of the new soil, it was much faster with the EI dosing.

OK, well, Carbo=CO2 so one can get away with a dark green DC because the tank is being supplemented with Carbo which has no effect on the DC color, but has an effect on CO2 assimilation by the plant.

We also must clarify what kind of water is being added to the tank during the water change. Is RO water being added or is it tap water added? If tap water is being added what is the water analysis?
Actually, initially he did not fertilize.
In this post he explains that the plants were not growing fast enough for his taste and that a week after starting the fertiliser, the growth speed had improved. But I agree that we don't know if it was the glutaraldehyde itself or another element which improved the growth.
During water changes, he only uses RO water with GH+ (no macro).

Why would that be the default guess? There is no surface ripple because the pipe is below the surface and is pointed straight ahead. What does it say on paper exactly?
I asked him in a thread dedicated to the new version of his tank and he made a video. The lily size, position is similar.


There is only a superficial relationship between growth rate and plant health. This is a mistake that many people make because they assume the opposite. Plants can grow very quickly if the lighting is very high and they will exhibit deficiency because all the products necessary for health are not present in enough abundance. CO2 and nutrients are required for plant health.

The conditions described for this tank indicates that the lighting perhaps was not as high as supposed, which can easily explain the slow growth and if that is the case, then the demand for nutrients and CO2 was also not as high as expected, whereas nutrients were present in abundance and CO2 was being supplemented via gas and liquid.
Here we are. Maybe you should help me here because this difference is not clear to me. In this tank we get a certain amount of light, unchanged, and with more fert, plants growth faster. With less initially, they grew slower but no deficiency.
We could get similar exemple elsewhere : Denis Wong here indicates to use close to 100 micromoles at substrate level to grow carpet plants without injected CO2.
tiger15 below did the same.
Without CO2 we should expect the grow to be limited, but they get healthy grow. Where these tanks succed having healthy plants with limited grow whereas many will get trouble and deficiency with less light?

To be continued tomorrow (I am slow to write in English).
 
I'm not sure to understand this sentence. 100 times the weekly dosage of EI ? But the availability of elements is not the same as it is in the soil? If not I guess Tom Barr using aquasoil would not need to fertilize in parallel as he does? I have recently rebuilt my tank, before the change I had an old aquasoil (5 years) with EI dosing, the plants grew very fast. The new version got a new aquasoil and now a lean dosing, I have to say that the plants are growing much slower now despite of the new soil, it was much faster with the EI dosing.
Yes, that number is correct. Aquasoil is just clay soaked in a nutrient solution and then dried by baking. When you add water the nutrients slowly leach from the clay into the water Column so that nutrients become available from both the sediment as well as from the water. I use Aquasoil as well and I always dose EI. No, one does not "need" to dose EI but that is our option as it ensures we do not fall short. We cannot say for sure exactly what the cause is for the growth rate. The difference could be explained by a variety or combination of factors, including CO2 and light differences as well as flow/distribution differences. If you believe that New is less potent that Old then you would need to set up multiple tanks as equally as possible and then determine the difference. What we do know is that there are hobbyists who follow the ADA technique of Aquasoil or Aquasoil+Powersand and add only minor amounts of potassium for the first year or so and have success. There are also others that fail due to reasons we cannot be certain of due to lack of complete data.

Yes, it's difficult to tell exactly what the flow rate is as the pipe is not directed at the plants but we can see some ripples at the surface.

Here we are. Maybe you should help me here because this difference is not clear to me. In this tank we get a certain amount of light, unchanged, and with more fert, plants growth faster. With less initially, they grew slower but no deficiency.
We could get similar exemple elsewhere : Denis Wong here indicates to use close to 100 micromoles at substrate level to grow carpet plants without injected CO2.
tiger15 below did the same.
Without CO2 we should expect the grow to be limited, but they get healthy grow. Where these tanks succed having healthy plants with limited grow whereas many will get trouble and deficiency with less light?
What we do know is that by far, there are a greater number of hobbyists who use high PAR values (again, we do not have the data) and have poor diffusion and flow and the results are algal blooms. We know that when the CO2/flow/distribution are corrected the tank becomes healthy again. We see, without exception that when the hobbyist reduced the light intensity the algae subsides.
We do not have the PAR values on many of these LED scenarios, only percentages of full value. There is very little correlation between the type of problems encountered versus the growth rate. In some cases the plants grow quickly but there is deficiency syndromes. In other cases the plants melt away or do not grow. Poor CO2 has many faces and that face depends on the severity of the deficiency, whether the deficiency occurs suddenly or over long term and what the condition of the plant is at the time the deficiency occurs.
So for example, here is a situation where Didiplis diandra is generally healthy but is suffering mild CO2 deficiency resulting in hair algae. The plant also grows at a good rate because CO2 at that location is good but not great:
8394062941_83e3543105_c.jpg


So it isn't a matter of growth versus deficiency. A plant can have both fast growth and deficiency, fast growth and no deficiency, slow growth and deficiency or slow growth and no deficiency. Any combination is possible depending on severity and initial conditions.

I think Denis Wong is saying very similar things. He also mentions that the most difficult time is at the beginning. This is where many tanks fail , because they stress the plants at the beginning when the plants are weak. As plants mature they become stronger and are more able to resist environmental stresses. What I disagree with is the connection he makes between growth rate and plant health. He might be using the word "growth" to mean "healthy growth" not necessarily "fast growth".

Cheers,
 
Hello,

I have a question about aquarium environment, not I new topic about lean vs rich dosing, but I would like to understand why in some cases (the majority), if the fertilization is inadequate, plants will show deficiencies (and we will get algae) while in others, we will be able to get a limited growth of the plants, which could be (very) slow but in perfect health (without algae).

The first case is very common, an aquarium where fertilization is insufficient, or often when the CO2 is not optimal, or with an incorrect water flow ... This results in unhealthy plants, with often visible deficiencies (and most often with algae). What's interesting here is that the plants can show deficiency (I guess because of an element not present in sufficient quantity to cover their needs), but they still continue to grow, sometimes even quickly. The deficiency is clearly visible but the missing nutrient does not always seem to highly affect its growth rate, or at least does not block the growth of the plant.

On the opposit, I took a specific tank as exemple, from a french forum where I often discuss. Here is the tank :
1556899110-img-1588.jpg

With the topic here (in french) : Aquascape Optiwhite 90x45x45

In this tank, the plants are mostly healthy (in my opinion, at least much better than some tanks showing deficiencies with a growing speed which remains significant), we do not get visible algae and plant growth is severely limited. For illustration here is the tank 1 month later without any trim :
1559503494-img-1633.jpg

Look pretty similar I think.

For the analysis :
The tank is 90x45x45 cm (35"x18"x18") 180 L (48 gal)
Light : Chihiros A901 plus, 100% intensity, 8 hours/day, pretty close to the surface. According to the data here, I think the PAR value should be arround 100 at the substrate level, maybe a little bit more.
CO2 : 2 bubbles/sec, cheap diffuser, under the filter outlet (I think he loses many bubbles), drop checker < green (dark green or blue), no pH analysis, I think we can consider the diffusion as low / poor.
Water changes : 20 % per week
Soil : ADA aquasoil 1 year old
Fert : nothing for the first year. After 1 year, he started to fertilize, not because he identified deficiencies but because the plants were growing too slowly to his taste. Then he added daily (but he said he often forgot) easy life products :
1.5ml nitro = 1 ppm NO3
1ml fosfo = 0.03 ppm PO4
1ml ferro = 0.07 ppm Fe (not daily)
1ml carbo
1ml profito = 0.016 ppm Fe
1ml potassium = 0.27 ppm K (not daily)
Flow : pretty strong eheim filter on paper but from what I saw on these videos, very little movement in the plants and almost no surface ripple, so low flow I guess.

Everything seems low in comparison to what we can see on other tanks which could present deficiency issues.

My question is: according to you, how an aquarium like this one will succeed in having a very slow growth of plants, very close to stop growing completely, but without deficiency, whereas in other tanks, plants can show deficiencies while continuing to grow?
The Liebig law talks about the scarcest resource as limiting factor but the line between limitation of growth and deficiency is no longer very clear to me.

And then, how to create a such environment where fert would only regulate plants growth, without deficiency issue (and algae) in parallel?

Thank you !
The Rotala is very red which maybe a clue. It reminds me of Filipe Olivera's kitchen tank. He lean doses and uses very high light. It seems a bit paradoxical but in the case of his kitchen tank high light has actually slowed plant growth, probably because it's trying to avoid photodamage. This means the plant stays longer under the light without growing new leaves so the existing leaves become reder, again a mechanism to avoid photodamage. I think this is possibly what is happening with the tank in the OP.



 
Hello, welcome back :)

Hi,

Having read the original forum post that you reference I think most things can be explained.
I'd agree the rate of stem growth isn't super fast, but there is growth, and the original poster mentions on several occasions that trimming is being done.

Admittedly I've had to use Google translate to read the French post, but from what I can gather the scape pictured is at least in part a re scape, I can't determine how long the stems have been planted but the carpet was only 3 weeks old in this pic from the 10th April.
If we then look at a picture posted the following day you can see the rotala green has had a heavy trim.
Fast forward to the 3rd May and we see quite a bit of growth. (I think this is the first picture you showed)
And finally the 2nd picture you show from the 2nd June. I've quoted the op's comment that accompanied this pic.
"Few changes in 1 month. I did a big pruning 3-4 weeks ago, mowed the grass to even out the height a bit, transplanted the pogostemon erectus to make a second grove on the right and that's about it."

So we can see that pruning is taking place and if we look at the pictures from 11th April to 2nd June, we can clearly see a good bit of growth.

Regards nutrients, yes the op is a bit haphazard with dosing, sometimes adding more, sometimes adding less, and sometimes forgetting to dose at all, and always on the lean side.
However 20% of the water is replaced every week with re mineralised ro, the product used is called gh+, I don't know what that product contains or how much is used, but suspect it contains calcium, magnesium and possibly potassium.
There's also a fairly decent fish stock of 40 x-ray tetra and 8 ottolincus, along with the food they're given could this be supplying some of the nutrients seemingly lacking?

Hope this a least answers some of your questions.

I agree, thank you to put it forward. There's still a decent growth. Actually, I think pictures are not in line with the moment of interest, when he identified a growth too slow for his taste and he started fertilizer (which immediatly improved grow speed, according to him). And I think we are far from what we can get with EI. On the previous version of my tank, I was dosing EI , the rotalas growth up to 30 cm per week and lowering CO2, I could easily end up with deficiency, despite a not so slow growth rate.

I don't know what's exactly in the gh+, I think he uses this product, but it is indeed possible that this product provides potassium, in addition to magnesium and calcium. The fish stock should also provide macro, but I think one element was bound to be limiting growth as he indicates that growth has resumed well after the start of liquid fertilisation (lean).

Yes, that number is correct. Aquasoil is just clay soaked in a nutrient solution and then dried by baking. When you add water the nutrients slowly leach from the clay into the water Column so that nutrients become available from both the sediment as well as from the water. I use Aquasoil as well and I always dose EI. No, one does not "need" to dose EI but that is our option as it ensures we do not fall short. We cannot say for sure exactly what the cause is for the growth rate. The difference could be explained by a variety or combination of factors, including CO2 and light differences as well as flow/distribution differences. If you believe that New is less potent that Old then you would need to set up multiple tanks as equally as possible and then determine the difference. What we do know is that there are hobbyists who follow the ADA technique of Aquasoil or Aquasoil+Powersand and add only minor amounts of potassium for the first year or so and have success. There are also others that fail due to reasons we cannot be certain of due to lack of complete data.
Ok, thx, but except for the first weeks, we could expect that the nutrients, leached from the clay into the water Column, to be lower than EI dosing level (?)
Not sure that my new soil new is less potent that the old one, but from what I could see in my tank (with this single and limited trial), old AS + EI show faster grow than New Soil + lean dosing.

What we do know is that by far, there are a greater number of hobbyists who use high PAR values (again, we do not have the data) and have poor diffusion and flow and the results are algal blooms. We know that when the CO2/flow/distribution are corrected the tank becomes healthy again. We see, without exception that when the hobbyist reduced the light intensity the algae subsides.
We do not have the PAR values on many of these LED scenarios, only percentages of full value. There is very little correlation between the type of problems encountered versus the growth rate. In some cases the plants grow quickly but there is deficiency syndromes. In other cases the plants melt away or do not grow. Poor CO2 has many faces and that face depends on the severity of the deficiency, whether the deficiency occurs suddenly or over long term and what the condition of the plant is at the time the deficiency occurs.

So it isn't a matter of growth versus deficiency. A plant can have both fast growth and deficiency, fast growth and no deficiency, slow growth and deficiency or slow growth and no deficiency. Any combination is possible depending on severity and initial conditions.

I think Denis Wong is saying very similar things. He also mentions that the most difficult time is at the beginning. This is where many tanks fail , because they stress the plants at the beginning when the plants are weak. As plants mature they become stronger and are more able to resist environmental stresses. What I disagree with is the connection he makes between growth rate and plant health. He might be using the word "growth" to mean "healthy growth" not necessarily "fast growth".
Totally agree, I like to experiment in my tank and came comes to these conclusions as well. With EI dosing, I tried lowering KNO3 (slowing switching to KH2SO4) to induce red pigmentation on my rotala, it quickly ended-up in an obvious deficiency. I tried to lower CO2 and plants quickly felt bad. And plants were still growing fast. Lowering the light worked, but I lost the colors...
But some people seem to reverse all these rules and get good results with slow grow and colored plants...

Tim gave another good exemple with Filipe Oliveira. If we do the math, his dosing regimen is very lean. And he often uses strong light. In the tank below, he set up the tank below with 2x Twinstar EU900SA V2.


Here are the PAR value I was able to mesure with 1 feature (twinstar 900SA V1, which is a little bit weaker than the V2):
30 cm : 200
40 cm : 140
50 cm : 107
60 cm : 80
70 cm : 62
80 cm : 50
1m : 32

Liebig's law states that growth is dictated not by total resources available, but by the scarcest resource (limiting factor). The word "deficiency" seems to be linked with this scarcest element and he doesn't talk about plant deficiency (correct me if I am wrong).
With EI, if we try to limit growth with CO2, we get deficiency.
I had a hypothesis (which could be wrong). As already explain here, with EI, if CO2 is poor, the plant will suffer because of the fluctuation of the CO2 (rubisco). As the demand for plants is high, CO2 have to be strong and consistent, the flow must be optimal to keep good gazeous exchanges and a stable CO2 level.
With Diana Walstad method, CO2 could be very low, but the plants are ok because without CO2 injection, the fluctuation is low in comparison (highest concentration is close to the lowest). Less trouble because of the rubisco for the plant (I guess), less energy used to be in line with the CO2 level always changing.
Maybe it could be the same for nutrition. With EI, you don't get trouble with nutrition because there's no limitation. If you lower a little bit below the non-limited growth level, the concentration of this element start to fluctuate. This fluctuation could be painful for the plant to grow properly and visible deficiencies occured.
But maybe if you go (very) low, the fluctuation will be also low, and this situation could be ok for the plant, knowing that she has to grow with low nutriment.
Aquasoil, or other soil with high CEC capacities, should be perfect to level out any variations in nutrients that might rise a little at night and fall during the day with the plants consuption.

What do you think about that?

Thank you ;)
 
Liebig's law states that growth is dictated not by total resources available, but by the scarcest resource (limiting factor). The word "deficiency" seems to be linked with this scarcest element and he doesn't talk about plant deficiency (correct me if I am wrong).
With EI, if we try to limit growth with CO2, we get deficiency.
I had a hypothesis (which could be wrong). As already explain here, with EI, if CO2 is poor, the plant will suffer because of the fluctuation of the CO2 (rubisco). As the demand for plants is high, CO2 have to be strong and consistent, the flow must be optimal to keep good gazeous exchanges and a stable CO2 level.
With Diana Walstad method, CO2 could be very low, but the plants are ok because without CO2 injection, the fluctuation is low in comparison (highest concentration is close to the lowest). Less trouble because of the rubisco for the plant (I guess), less energy used to be in line with the CO2 level always changing.
Maybe it could be the same for nutrition. With EI, you don't get trouble with nutrition because there's no limitation. If you lower a little bit below the non-limited growth level, the concentration of this element start to fluctuate. This fluctuation could be painful for the plant to grow properly and visible deficiencies occured.
But maybe if you go (very) low, the fluctuation will be also low, and this situation could be ok for the plant, knowing that she has to grow with low nutriment.
Aquasoil, or other soil with high CEC capacities, should be perfect to level out any variations in nutrients that might rise a little at night and fall during the day with the plants consuption.

What do you think about that?
Hi Alex,
Yes, I agree with your hypothesis. Rubisco production has an inverse relationship with available CO2.
I should mention however, that although Liebig's law does address the limiting factor for growth, we have to be careful how we apply this because not every nutrient is responsible for growth, and even those nutrients which are responsible for growth do not affect growth in the same way or to the same extent. So for example Carbon has the largest effect on growth by a large factor, Nitrogen to some extent and, to a much lesser extent Phosphorus and Potassium. The micronutrients do not have much effect. The nutrients, NPK, normally dosed together each have a "reciprocal" effect on each other however. Adding CO2 causes an increased uptake of Nitrogen and adding more Nitrogen causes a higher uptake of CO2. The same is true of N->P and P->N.

Another factor is that adding more CO2 causes the plants to produce LESS Rubisco and the reverse is true. So when the CO2 is high, then even minor fluctuations in the CO2 causes a deficiency because the plants have become less efficient in gathering CO2 as a result of the low production of CO2.

The same may apply to NPK but I do not know for sure as plants will uptake high levels of NPK and will store them for future use, so I do not think fluctuations in NPK has much of an effect because their consumption is not as fast as consumption of CO2. Also, some of the nutrients, P in particular is recycled rapidly and K is not attached to any structure. K lives in the "bloodstream" of the plant and is always in motion. So C and N are the primary elements responsible for growth. C builds structure and N builds proteins, enzymes and other critical molecules. Deficiencies in C and N are more likely to be observed as growth problems while deficiencies in P and K will have other characteristics not necessarily related to growth.

As a result of these complications and interactions it's very difficult to draw precise conclusions about the cause and effect of what we observe.

As you mention, sediments having high CEC will definitely help in cases where the water column dosing may fluctuate. Rooted plants are able to uptake NPK, traces and even CO2 from the sediment.
Ok, thx, but except for the first weeks, we could expect that the nutrients, leached from the clay into the water Column, to be lower than EI dosing level (?)
Well probably the concentration leached into the water is lower than actual EI dosing, remember that the N vehicle of Aquasoil is NH3/NH4, which is 4 times more potent than NO3 used in EI. The sediment continues to leach nutrients into the water due to the high initial concentration level.

Cheers,
 
Tim gave another good exemple with Filipe Oliveira. If we do the math, his dosing regimen is very lean. And he often uses strong light. In the tank below, he set up the tank below with 2x Twinstar EU900SA V2.
I rememeber watching Oliviera's video when he says he uses a lot of root tablets showing Seachem Flourish Tabs. It's this video - /watch?v=wtH44vCjW2Y .
So it's lean dosing, but not so lean...
 
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