Journal Marcel's next experimental design - suggestions welcomed

  • There is also the eternal debate on lean dosing versus EI dosing, so also for that a controlled test environment could have a huge benefit for our hobby. Is toxicity real, and can we demonstrate it?
This debate between lean vs rich dosing continues to fascinate me. Strong opinions on both sides, but I really dont think there should be. The "lean" and "rich" refers to whats in the water column. The fresher/richer the substrate is, the less nutrients need to be in the water. Nutrients are still available to the plants the only difference is where theyre at

Take my sand tanks, especially the Dutch. There is no magic nutrient ratio, or kh/ph/co2 level that will make those tanks run on a lean water column. Because thats the only place the nutrients are, But throw a fresh rich soil in there and all of a sudden there can be very little nutrients in the water

So I dont think the two methods are in competition. The problem arises when the lean doser having good success tries to impose their lean method onto folks who need a rich water column. And visa versa. They are just two different set ups. Lean can work if youre set up for it with a richer sub. Rich works if youre not

I would also add that rich dosing doesnt cause any problems even with a rich sub. Plants will grow faster and fatter, many will have less bright colors than can be achieved otherwise. But Ive never seen rich water cause a plant to go bad, stunt, be algae prone whatever. In fact whenever Im having a problem, if I know the co2 is good, and the tank is clean, my first go to move is usually raise macros. I am constantly surprised how often that works, for both my sand and soil tanks

The lone exception to this is ammania varieties (and perhaps Rotala serpylifolia) Ammania simply does not do well in a rich water column. Its like trying to raise tetras in salt water. Theyre just not buit for it. They can do fine even with inert sub as long as the water stays lean, but this lean water wont be enough to make many other species happy with inert sub

Also Im mainly speaking about macros here. Micros can certainly be overdone and cause problems. But a lot of the micro problems we see are related to not having the right Fe chelate for our ph, or using crap products like csmb that arent designed for aquarium plants to begin with

And no nutrient is harmless. We cant run 200 ppm of K without it causing a problem, call it toxicity or whatever you like. For one thing, if nothing else it throws the ionic balance way off. So there is a very loose and general, dare I say optimum, ideal ratio for everything to be in

These ratios can change a little based on other factors. Rich subs can get by on far less n03 for example. Im not sure there is one golden ratio of anything that will work in every single tank. But if ratios didnt matter and there was no such thing as too much we'd all be dosing 40/40/40, 3-4 ppm Fe, and talking about something else right now

This just my opinion based on what Ive seen over the years in my own tanks. I dont have any scientific papers to back this up ;) so tifwiw
 
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I apologize, but I give up further attempts to clarify my intent. With my limited powers of expression, I don't think I'm capable of it.
I really look forward to your experiment @Marcel G , and especially thank for your open mind discussing this. What you are doing is unique, and in many ways opens new thinking and learning. Greatly enjoy this thread!
 
This debate between lean vs rich dosing continues to fascinate me. Strong opinions on both sides, but I really dont think there should be. The "lean" and "rich" refers to whats in the water column. The fresher/richer the substrate is, the less nutrients need to be in the water. Nutrients are still available to the plants the only difference is where theyre at

Take my sand tanks, especially the Dutch. There is no magic nutrient ratio, or kh/ph/co2 level that will make those tanks run on a lean water column. Because thats the only place the nutrients are, But throw a fresh rich soil in there and all of a sudden there can be very little nutrients in the water

So I dont think the two methods are in competition. The problem arises when the lean doser having good success tries to impose their lean method onto folks who need a rich water column. And visa versa. They are just two different set ups. Lean can work if youre set up for it with a richer sub. Rich works if youre not

I would also add that rich dosing doesnt cause any problems even with a rich sub. Plants will grow faster and fatter, many will have less bright colors than can be achieved otherwise. But Ive never seen rich water cause a plant to go bad, stunt, be algae prone whatever. In fact whenever Im having a problem, if I know the co2 is good, and the tank is clean, my first go to move is usually raise macros. I am constantly surprised how often that works, for both my sand and soil tanks

The lone exception to this is ammania varieties (and perhaps Rotala serpylifolia) Ammania simply does not do well in a rich water column. Its like trying to raise tetras in salt water. Theyre just not buit for it. They can do fine even with inert sub as long as the water stays lean, but this lean water wont be enough to make many other species happy with inert sub

Also Im mainly speaking about macros here. Micros can certainly be overdone and cause problems. But a lot of the micro problems we see are related to not having the right Fe chelate for our ph, or using crap products like csmb that arent designed for aquarium plants to begin with

And no nutrient is harmless. We cant run 200 ppm of K without it causing a problem, call it toxicity or whatever you like. For one thing, if nothing else it throws the ionic balance way off. So there is a very loose and general, dare I say optimum, ideal ratio for everything to be in

These ratios can change a little based on other factors. Rich subs can get by on far less n03 for example. Im not sure there is one golden ratio of anything that will work in every single tank. But if ratios didnt matter and there was no such thing as too much we'd all be dosing 40/40/40, 3-4 ppm Fe, and talking about something else right now

This just my opinion based on what Ive seen over the years in my own tanks. I dont have any scientific papers to back this up ;) so tifwiw
Great post Joe!

I've always said a well run tank can get by pretty well with a fairly wide range of nutrients. I look at it as enough but not too much. Plants will adapt.

In my experience more important is getting everything else right. Light, CO2, flow, maintenance, horticulture, etc. I look at nutrients as tuning up a car. You can't tune an engine if isn't running. And if you don't get the other things right even the most perfect dosing scheme won't save you.

Like you based on my personal experience and interaction with hundreds of other hobbyist over the years.
 
I would also add that rich dosing doesnt cause any problems even with a rich sub. Plants will grow faster and fatter, many will have less bright colors than can be achieved otherwise. But Ive never seen rich water cause a plant to go bad, stunt, be algae prone whatever ...
Here again I would disagree. Look at the photos and parameters of my aquariums:
parameters-6.vs7.png
The first aquarium had much less of most of the nutrients in the water than the second. And you can see the result for yourself. Both aquariums used the same organic substrate capped with sand:
tanks-6.vs7.webp
wallichii-srovnani-10.den-s.jpg
Just to illustrate that rich dosing definitely can cause problems under certain conditions.
 
I really look forward to your experiment @Marcel G , and especially thank for your open mind discussing this. What you are doing is unique, and in many ways opens new thinking and learning. Greatly enjoy this thread!
Even though we're on our third page of discussing this here, I don't feel like it's gone anywhere, unfortunately. We are debating all sorts of things here, but the "vital parameters" proposals that are at the heart of my interest remain sadly outside your interest. I don't blame you, of course (you just have a different perspective on it, which happens), but for me personally, staying in this discussion any longer misses the point. I spend a disproportionate amount of time explaining all sorts of things, but it doesn't lead to the desired end. Anyway, thank you all very much for your contributions.
 
Here again I would disagree. Look at the photos and parameters of my aquariums:
View attachment 5985
The first aquarium had much less of most of the nutrients in the water than the second. And you can see the result for yourself. Both aquariums used the same organic substrate capped with sand:
View attachment 5986
View attachment 5987
Just to illustrate that rich dosing definitely can cause problems under certain conditions.
I do understand what youre saying. And as you know Ive followed your experiments from the beginning with great admiration and respect for your thoroughness.

But for example these tanks with the wallichii, I just think there are too many other variables in play to blame the poor growth and algae on macros alone. What kind of organic substrate would be my first question, but I wouldnt know what to do with the answer if you told me. Are the tanks mature or brand new? Dosing a little NH4 in the water? Tricky business, besides plants love that at the roots and just a little excess in the water makes gda

The tank with some of them growing well has problems too, algae and poor growth. If high macros was the problem you should be able to fix those plants and the tank simply by reducing further. Isnt that a fair assumption?

I dont see a healthy control where the tank is clean, algae free and the plants growing well. What you have is 6 different examples (very good ones) of how wallichii responded to a few specific things in these particular set ups. It does not, imho, establish the fact that wallichii doesnt like high macros

These are growing in blasting sand, 5-6 KH, and macros at or near ei levels. Its two feet tall in a standard 75 gal, decent color and the stems are good all the way to the ground

rotala-wallichii-1.jpg

* Im just tossing ideas back and forth with you bro. Not trying argue one way or the other
 
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I just think there are too many other variables in play to blame the poor growth and algae on macros alone ... It does not, imho, establish the fact that wallichii doesnt like high macros.
I find your arguments persuasive, so I admit my mistake and retract my previous conclusion that "rich dosing can cause problems". With a high degree of probability, other factors were to blame. Thank you very much for correcting my misconception. (y):coffee:
 
I'm playing with Rotala wallichii (mainly) right now in the meantime and I ran into an interesting problem. I know it probably won't show up very well in this picture, but I'm solving a mystery right now => see the picture:

Edit: I originally used low macro without bicarbonates (i.e. KH=0) in all my aquariums. This condition is still maintained in tank #4. I then increased the macro in tank #3 (to near non-limiting values) and did the same in tank #1, but added a little bicarbonates there (i.e. KH=1). The result is interesting: while in tank #4 R.wallichii grows well as usual (it always has), in tank #3 after increasing the macro-elements its condition deteriorated rapidly (stunted growth). However, in aquarium #1, where I also increased the macro-elements, this condition did not occur, which is really interesting. The only difference there (compared to aquarium #3) is the added bicarbonates. But what could the bicarbonates have done to protect the R.wallichii from stunting?

IMG_20240906_183401.webp

Tank #1 = High macro + KH=1 => good growth of R.wallichii
Tank #3 = High macro + KH=0 => bad growth of R.wallichii (stunting)
Tank #4 = Low macro + KH=0 => good growth of R.wallichii
PS: Ignore tank #2 because it doesn't fit (it has different parameters).
All tanks get the same micro (using strong chelates), and there is no substrate of any kind.
 
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Hi @Marcel G
Long time follower of your work here (both on the forums and on your website). I really appreciate your contributions to the hobby's pool of knowledge.

That experiment with Rotala wallichii is interesting. The way I interpret the results is as follows:
  1. This plant has a reputation for being able to do well on lower macros. i.e. it does not need much to produce vertical growth. Tank #4 seems to confirm this once again.
  2. I could be wrong, but perhaps the higher macros increased the plant's carbon demand. And since tank #1 contains an extra carbon source; i.e. bicarbonates (which we know some species can utilize, albeit at a higher energy cost), it had an advantage over tank #3. This would congirm that:
    • Wallichii is one of those species that can scavenge some carbon from bicarbonates when CO2 (which will be preferred when present) is too low. (You mentioned you grew it in low tech.)
    • The more we go to the rich/EI end of the dosing spectrum, the higher demand is on carbon and the more CO2 needs to be tuned correctly. This is why most people who fail with EI type of systems, they do so because their CO2 is not really optimized even if they think it is. This is because CO2 injection is the trickiest thing in the hobby to tune with certainty to higher levels. Even the pH drop method can be misleading if you don't really know the CO2 concentration that you're starting with and just make assumptions about it. But that is another topic.
So it can do well in lean or rich dosing, like in Joe's (@Burr740) tank above.

Personally, when growing this plant I noticed that:
  • It's one of those plants that do well with very high CO2 levels and low KH water. The higher CO2 makes it less dependent on nutrient levels. (Contrary to some other species where if you push the CO2 and light to high levels, they demand high macros and if you don't provide that they run into issues in my experience.)
  • Even when macros bottom out and some other species (like many Ludwigias) start to complain, Wallichii does well. It seems comparatively good at scavenging lower nutrients.
  • It's one of those species that do appreciate NH4 as a nitrogen source when it's available. (The preference of NO3 vs NH4 of course being species dependent.)
20231011_162727.jpg

By the way, one thing that is perhaps less accounted for in experiments like these is adaptation stress. When switched between overall rich and lean environments, or even just high versus low nitrogen, CO2 versus no CO2, high CO2 versus low CO2, etc... plants can go through a shock period. This is often expressed as stunting or a period of slow growth. Only new tissue is adapted to the new environment and representative of the plant's true potential within it. So when I see these experiments, one of the questions I ask myself is "from what environment did these stems come from?".

This is especially the case when relying only on foliar feeding since the older leaves that are already better adapted to the test's conditions will be able to uptake nutrients more efficiently, resulting in better overall growth.

Having said that, these experiments are great.
 
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Regarding Ammania species (pedicellata golden being the usual suspect) which you seem to want to better understand through new experiments. I've heard all kinds of theories for why they notoriously stunt, which include but are not limited to nutrient levels. Some of these theories are:
  1. They're sensitive to high potassium levels. (Popular belief in the European Dutch tank scene, but I even heard Dennis Wong say this in an interview.)
  2. They're sensitive to high NO3 in the water column. (I've seen some people claim 10ppm being the limit.)
  3. They're not sensitive to absolute levels but rather to fluctuations in nutrient levels, such as after performing water changes. Marian Sterian leans towards this. So he says smaller water changes and paying special attention to reconstituting the nutrient levels after a water change as well as relying more on a rich substrate (since that fluctuates less) are all things that can help. He grew the best submerged pedicellata golden a few years ago, but he told me that he couldn't reproduce that quality of growth these days and unfortunately does not remember the conditions that lead to such a growth back then (he did not journal the tank's specific conditions). He can still grow it, but not like he did back then, which was incredible:
    297640455_745185233368754_48412716632176177_n.jpg 297490324_1101452540483760_272210132645566558_n.jpg
  4. Another claim is that, in nature it grows emersed and is rarely found submersed. (I grow ammanias emersed, they're easy to grow that way and grow like weeds when well fed and well lit.) As such, they're not good at foliar uptake of nutrients and are much better at root feeding from the substrate combined with unlimited CO2 from the air (+400 ppm). So a rich substrate, lean water column and stable CO2 is key.
Personally, I don't buy #1 and #2. There is some truth to #3 and #4.

I once saw a garden tank with amazing plant health, including pedicellata golden. When I asked the guy what his secret was, he said: "The key is: slow growth."

I've been thinking about that for a while. After doing some research, it turns out that slowing down plant growth in terrestrial plants is a thing, particularly in landscaping where it is not the speed of yield that is prioritized but rather the health and aesthetics of plant growth. The use of PGRs (plant growth regulators) that slow down growth, as counterproductive as that sounds, even when the plants are well fed allows the plants to spend less of their energy budget on making new growth and more on maximizing the quality of the growth: higher resistance to stress and immunity to disease, bushier with better form and coloration, and longer natural age of older leaves (i.e. older leaves deteriorate slower). There's a lot of information on this relating to landscaping, lawn keeping, etc. Plants have a limited energy budget, which they can spend on different things (vegetative growth, vs root growth, vs reproduction/flowering, vs resistance to external stress/disease/competitors). Toward what they can allocate more energy is something that we can somewhat control. (Opting for rushing to reach surface of the water at all costs in order to grow emersed under unlimited CO2, make flowers and reproduce, is usually their default priority in submerged conditions, particularly for stem plants.) I find this fascinating. How growth rate regulation can be applied to planted tanks is something I'm still investigating.

Back to the pedicellata, I've struggled like most to keep it in my high energy (high nutrients, light and CO2) long term, even with rich soil and good maintenance. Some of the stems constantly stunt and have to be re-done.

Recently, I planted a few stems in an 8 gal beta fish planted tank just to see what happens. This tank has:
  • Low PAR light
  • Low CO2 levels (from pressurized CO2 injection) which I don't even bother to measure. I just know there is some CO2 for the plants there. If I had to guess, I'd say probably no more than 10-15 ppm.
  • Low nutrient levels dosed by feel. Every couple of days, I'll dose a few drops of macros and micros from the DIY bottles that I use for my main larger tank. No idea what ppms this adds and I don't count the drops/ml's I'm adding. If some GDA starts to appear on the glass, I'll stop adding macros for a few days.
  • The betta is well fed and water is changed about once a month.
  • Black diamond blasting sand with no root tabs!
Pedicellata golden has been growing slowly, but perfectly fine with zero stunting in this tank. No big thick stems and leaves, but zero issues top to bottom. Same for Ammannia gracilis in the same tank.

Right next to this tank is my super spoiled high energy tank with almost non-limiting everything and fast growth, but stunting ammannias... (although all other species are doing well). I ultimately gave up trying to grow them in the big tank for now.

So my theory is this:

It's not about the potassium or some magic NO3 level or lean vs rich water or neutral vs rich sediment. This species is not good at regulating its own growth rate when pushed to grow fast. I.e. beyond some growth rate threshold, it'll try to run fast but trip over itself and fall. It needs to be forced to grow slowly when grown submerged. This can be done using Liebig's law and a lower energy tank, while at the same time not allowing any key nutrient to be missing.

This is the best explanation I have for it so far that explains my own experience as well as the other explanations that some other hobbyists came up with. From why it grows great in Tom's garage tanks, to why some lean dosing fanatic in Germany swears that it needs low [insert nutrient] or [insert arbitrary "magical" ratio that forces a key growth ingredient to be limiting while at the same time never causing a deficiency].

In summary, I think that while we like to obsess about nutrient levels and their impact, the topic of growth rate and its implications on the success or quality of growth of certain species in this hobby I have never seen discussed. In contrast, it is well established and proven in commercial and home landscaping. We circle around this topic through direct/indirect/confounding factors, but never studied it directly. I don't know if my experience will help inform or inspire your future experiments, but there you have it.
 
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@Marwen a couple of very interesting and enjoyable posts above.

It's the reason I have always been a bit skeptical of these types of experiments. In a real planted tank there are a lot of forces at play. Light level, CO2 optimization, nutrients, flow, substrate type, substrate health/cleanliness, filtration, dissolved organics in the system, water change schedule, horticulture methods, plant mass in the tank, etc, etc, etc.

And it's not to discount the interest and value of such experiments, but I think it's a mistake to extrapolate those results to every tank. IMO every tank is a unique eco system. And having been around for a while every time you think you know something for sure, someone comes up with something that challenges that thought. Take my friend @sudiorca and his no CO2 tanks.

In reality much of this hobby is based on anecdotal evidence. There are no peer reviewed experiments being done that cover all of the variables in a planted tank. So I still think the best path to success is to study the methods of those that are successful and try to apply what you can learn to your own tank. And even then results may vary, as no two tanks are identical.
 
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IMO every tank is a unique eco system.
well that's not just an opinion, that's the actual FACT. I don't know if you got a chance to watch my AGA talk, I did briefly mention about microbial diversity among three of my tanks. Here is the figure from my talk to support your above statement.
Sudipta_bacteria and archaea -taxa_summary - Summer, 2022 - pH information.jpg

I collected samples from three of my tanks from different locations and successfully isolated and sequenced DNA from those samples. The y-axis of the above graph represents the relative abundance of microbial species in those tanks and x-axis represents the specific location from where the samples have been collected. All tanks are non- CO2 supplemented (don’t get confused by the labeling).

Few important points:

Composition of microbial community differs significantly within and among tanks.

Top and bottom layers of substrate showed equally high number of microbial species except the Non_CO2 tank (deep layer of substrate, 3 inch deep) – only 108 total species were found compared to more than 600 species for other tanks (even the filter of the same tank showed normal diversity). Escherichia/Shigella had ~94% abundance in that location. I was not able to isolate any DNA from the top layer of the substrate from that tank (I tried twice). I am not absolutely sure about the actual reasons behind the lack of life on the top layer, but Escherichia/Shigella could potentially be responsible for this. This tank also had algae issues for a long time and the low population/less diverse community could be the reason. I was able to stabilize the tank after I did massive uprooting and deep vacuuming of the substrate which not only removed a lot of detritus but it also removed most of those pathogenic bacteria which eventually gave the beneficial microbes a real chance to defeat the problematic ones.

Nitrifying bacteria – very low abundance (less than 2.8% abundance in all of the tanks tested).

I did another analysis recently for my recent setups and microbial community showed high diversity but many of the species have changed.


It is really important to understand that every single tank is different and it is IMPOSSIBLE to have an exact replicate even with same size tank, same substrate, light, water, filter, flow rate, fertilizer and same plants (number and species) etc. I have been performing biochemical experiments on bacterial enzymes for almost 15 years now and I am still searching for a perfect replicate even if I use the same enzyme and identical conditions. My experimental conditions are defined and I work with very few variables unlike a planted tank which has probably millions of variables (in fact there are hundreds and thousands of biochemical reactions happening every second inside a single bacterium, forget about a bacterial colony, now just imagine if there are 600 species of bacteria consuming and producing thousands of chemicals every second and everything is happening inside a closed glass box). I haven't even mentioned other microbes such as archaea, fungi, protozoa etc. or livestock and plants.
 
It's the reason I have always been a bit skeptical of these types of experiments. In a real planted tank there are a lot of forces at play. Light level, CO2 optimization, nutrients, flow, substrate type, substrate health/cleanliness, filtration, dissolved organics in the system, water change schedule, horticulture methods, plant mass in the tank, etc, etc, etc. And it's not to discount the interest and value of such experiments, but I think it's a mistake to extrapolate those results to every tank ...
I 100% agree with @GreggZ that "it is a mistake to extrapolate these results to every tank". I even believe that one of the greatest enemy of true knowledge (and progress in any field) is subjective interpretation of results, where the researcher (or observer) is seduced into drawing speculative conclusions. I myself am often an example of this, unfortunately. I research something, something comes out of it, and I often interpret it incorrectly, exaggeratedly ... drawing conclusions that don't follow. This can then lead us to practice or promote incorrect practices, and the truth escapes us.

Even worse, however, is perhaps "selective blindness", where we try to convince ourselves and others that certain specific parameters (e.g. high concentrations of potassium, nitrates or microelements, or too low or unstable CO2 levels, etc.) are behind the successful or unsuccessful growth of a particular plant. The problem with this approach is that it ignores the context and various principles.

When someone complains on a forum that a certain plant is not growing, one political party starts advising them to add CO2 and increase all the nutrients, while the other political party starts advising them the opposite. The result is a completely pointless war that has no winner.

If someone says that they can grow Ammannia pedicellata 'Gold' or Rotala wallichii in a nutrient rich substrate and in water with zero alkalinity and low nutrient concentrations, absolutely nothing can be concluded from that, because we do not know, what characteristics the substrate has, how much nutrients it has, what its redox is (which is important in terms of accessibility of some nutrients), what bacterial composition it has (as @sudiorca correctly points out), and last but not least what nutrients it has in the water and in what proportions. If I use a substrate with different properties, a different bacterial composition, a different nutrient content that can leach into the water, so that suddenly I also have a different water composition, then logically I can have a completely different result.

But that is why scientists are conducting controlled laboratory experiments to try to figure out (as challenging as it is) what factors are key and what factors are secondary => for example, when it comes to the bacterial composition of our substrates, perhaps it is not so much the exact species composition of the bacteria that matters, but rather their maximum diversity (if only one or two species overgrow, only then is there a problem). But if we are to figure this out, then we need to take all parameters into account (and not just the popular, "modern" ones). And in addition, we must try to understand the relationships between them. How nutrient availability affects pH and redox, what role bicarbonate or bacteria play, what happens to the bacteria when the substrate is disturbed during uprooting or sludging etc.

For example, if you look at my experiments with R. wallichii (a couple of years ago), a good observer will notice that in the first five experiments I used extremely low concentrations of chloride. And even though chloride is a micro-element, plants often use it in much higher amounts because of osmoregulation. So it is likely that the failure of these experiments was due to something as trivial as chloride deficiency. But nobody addresses chloride, and therefore virtually nobody noticed (myself not excluded). Similarly, in experiment #7, where R. wallichii grew poorly, I used extremely high doses of nitrate (54 ppm NO3), whereas in experiment #6, where R. wallichii thrived, I used only 10 ppm NO3. This in itself certainly means nothing, but in the context of the other parameters it certainly has some significance, even if we may not see it.

Bottom line: we should not consider individual parameters in isolation, but always in the context of other parameters. But to do this, we would have to start listing all relevant parameters (including Ca, Mg, Na, SO4, Cl, HCO3 ... pH, redox, substrate composition, bacterial composition, etc.) and not just the usual ones (NPK+Fe and CO2). Otherwise our discussions will be nothing more than pointless bickering that leads nowhere.

And a few more words on "Liebig's law of minimum" and "CO2 stability":

We are all familiar with Liebig's law of the minimum. According to this law, growth is not determined by the total amount of available resources, but by the amount of the scarcest resource (the limiting factor). Applying this to our aquariums, if a plant has 16 essential nutrients available in unlimited amounts, but 1 nutrient is in limited amounts, then its growth should be limited and it should grow as if all 17 of those essential nutrients were there in limited amounts. But that's not really the case. I would liken it to the fairy tale of Hansel and Gretel. Hansel and Gretel strayed from the evil Jezebel, who locked them up and fed them only sweets so they could get fat so she could bake them. So, we could say that Hansel ate an unbalanced diet with an excess of carbohydrates and fats. But this did not lead to limiting his growth (as he kept getting fatter), but to growth deformities => he was not developing properly. And I think it works the same way with plants with an unbalanced nutrient ratio. In my post #48 you can see, for example, if I increased the concentrations of all nutrients (except carbon, as @Marwen very correctly points out) in the third aquarium, then according to this law there should simply be a reduction in growth. While there was some reduction in growth, there was also an immediate deformity. So I would say that the plants continued to gobble up the increased concentrations of other nutrients, but because they lacked carbon, they were unable to build healthy organs from it, only deformed organs. But the increased nutrients continued to force them to grow, only the growth was deformed. But this would suggest that the right nutrient ratio [at least in some cases] may indeed matter.

I think there are similar misconceptions about CO2 stability. I'm not denying that it is certainly challenging for plants to make enough of the enzyme they use to get CO2, and the less CO2 available to them, the more telling it is. But fluctuations in CO2 concentration are perfectly normal in nature and plants are used to it. So some normal (non-extreme) fluctuation in CO2 levels is perfectly natural. But one observation is important to mention here: it seems to be extremely difficult for plants to "switch" between CO2 and HCO3 uptake. This means that if you add CO2 to the aquarium and the CO2 concentration never drops to such a low level that the plants have to resort to taking up carbon from HCO3, then there is nothing to worry about. However, if you are adding a large amount of CO2 (40+ ppm) to the aquarium and suddenly there is a shortage of CO2, then it will probably be quite a shock to most plants. And while the plants can "switch" from HCO3 to CO2 (or from little CO2 to high CO2) quite quickly, the reverse is said to take days or weeks. So if we are talking about a kind of "CO2 stability", then this certainly does not mean the normal fluctuations of CO2 during the day or night.

I will give an example with my R. wallichii: I have grown R. wallichii in water with low nutrient concentrations, zero alkalinity and no substrate all the time ... and it did great. Then I suddenly increased the nutrient concentrations in two aquariums. But in only one of them did I add extra bicarbonate. If I hadn't done that, I would have found that the increased nutrients caused an immediate deterioration in her condition, and I would have immediately concluded, wrongly, that the high nutrient concentrations were harmful to her. But in the other tank with high nutrient concentrations, I had extra bicarbonate which "caused" her to suddenly do well. As @Marwen aptly points out, the likely cause is that the higher nutrient concentrations sped up her metabolism, resulting in faster nutrient uptake. However, in an aquarium where the carbon concentration remained at its original (= low) level, this resulted in a carbon deficit. In the second aquarium, however, I increased the carbon concentration along with the other nutrients, and voilà, there was no deterioration. This beautifully illustrates how careful we should be in drawing various conclusions, especially when we are wounded by selective blindness, where we only see the parameters we want to and ignore the rest.

So until we start evaluating our aquariums holistically (i.e. really taking into account all parameters and not just the "popular" or "common" ones), then I think we will get nowhere and such a debate is meaningless for me personally.
 
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I was able to stabilize the tank after I did massive uprooting and deep vacuuming of the substrate which not only removed a lot of detritus but it also removed most of those pathogenic bacteria which eventually gave the beneficial microbes a real chance to defeat the problematic ones.
Great post and very, very interesting.

Myself and others I know have experienced similar things in our tanks. For some reason a tank is just not doing well. Plants are weak and algae creeps up. Seemingly every single other parameter is at good ranges that led to excellent plant growth in the past.

Just like you suggest in many cases a deep clean of the substrate turns the tank around. And I don't mean a quick vac. Like you said pulling up all plants and really deep cleaning it. Marian Sterian does this on a regular basis with his tanks.

I've long suspected that the bio activity in the substrate plays a far greater role than we give it credit for. And your tests seem to confirm that. Great write up and I feel there is more to be learned there.
 
Bottom line: we should not consider individual parameters in isolation, but always in the context of other parameters. But to do this, we would have to start listing all relevant parameters (including Ca, Mg, Na, SO4, Cl, HCO3 ... pH, redox, substrate composition, bacterial composition, etc.) and not just the usual ones (NPK+Fe and CO2). Otherwise our discussions will be nothing more than pointless bickering that leads nowhere.
This is great. I absolutely agree with you regarding what you said above and basically everything you mentioned in your reply. However, I just want to add temperature to that discussion as I have noticed very few people actually understand its importance in maintaining a successful planted tank for long periods of time. As a protein biochemist, I have to conduct all my experiments at certain temperatures and I have to mention that when I write a manuscript. Temperature plays a huge role regulating all the biological processes and it is extremely important to keep that in the mind. Here is one example from my AGA talk;

Screenshot (71).png

The two images above show bacterial phosphate binding protein (blue color bands in red box). Both are same protein and the bacteria was grown in the exact media (nutrients) but one grown at 18C (left) and one at 16C (right). As you can clearly see that the bands on the right image are significantly thicker than the bands on the left image. I have quantified the amount and there is almost 10 times more protein when the bacteria was grown at 16C vs 18C. Although the difference is only 2C but the results are significantly different. This is due to the fact that proteins undergo significant changes after they are formed, they need to be folded properly. Many proteins (enzymes) require complex metalloclusters which are synthesized by different enzymes and are inserted inside other enzymes for proper functioning. These are just two things, there are many other factors for optimum protein formation. So, when I tried to grow the bacteria at 18C compared to 16C, the cells were operating at faster speed and they had a hard time properly fold and form a functional protein, which resulted in significantly lower yield. Lower temperature allowed the bacteria to properly express and fold the protein which resulted in roughly 10 fold higher yield.

Plants are way more complex than bacteria and they have significantly more regulations and modifications when it comes to proteins and cellular processes in general. I can't think of conducting any enzyme experiments for my research without controlling the temperature.
Temperature is probably one of the most important but also the most neglected factors in the hobby IMHO.
 
I can't think of conducting any enzyme experiments for my research without controlling the temperature.
Temperature is probably one of the most important but also the most neglected factors in the hobby IMHO.
So what would you consider to be an "ideal" temperature? I've found my tank does better cooler rather than hotter.

My theory was that likely plant metabolism slowed as temperature decreased......but sounds like there could be a lot more to it.
 
So what would you consider to be an "ideal" temperature? I've found my tank does better cooler rather than hotter.
I don't think there is any particular temperature which will magically turn a badly operated tank and make everything healthy. However, there is definitely a range of temperature which allows for better plant growth, provided the operator is taking care of the other important factors as mentioned by @Marcel G . My observations are also similar to yours regarding cooler temperatures giving better results and that makes sense scientifically. I have found that my non-CO2 supplemented tanks perform better between 70-75 F. The example I provided above is probably one of the extreme scenarios. I don't think we need to be that specific when it comes to planted tanks. However, we should still keep that in the back of our mind and try to include temperature numbers when we discuss about tank parameters. Imagine a simple scenario where someone is trying to optimize fertilizer dosing based on someone else's successful planted tank (having similar plants and plant mass). If the reference tank is operating at 75F and the other tank at 80F (faster metabolism) then it would require more fertilizer to get similar results without facing algae and other problems.


My theory was that likely plant metabolism slowed as temperature decreased......but sounds like there could be a lot more to it.
I think it is still better to explain it that way as the details are little complicated if we discuss at molecular level and include livestock and microbes.
 
Referring to the title of this thread, "Next experimental design - Suggestions Welcomed", I agree to all said above but also wonder what would be the take away for experiments and advancement of knowledge in our hobby?

We will never fully understand R Wallichi or Pedicallata, nor will we know the complete set of parameters that may be needed to predict how they will do one hour from now, let alone one month. They and us share a common ancestor, probably 50% of DNA and our human biological complexity is higher than plants but still in the same ballpark. We hardly understand our own body, food and medicine, let alone these plants that have been researched much less.
In practical terms, we will also not have accurate data on all relevant parameters.
Farmers in the Middle Ages knew even less, but surpisingly still made progress in their understanding how to increase yield and avoid disaster.

So where natural science and philosophy meet, this is @Marcel G favourite, how can we advance our understanding to meet our goals for the aquarium hobby? Can any experiment be valuable, despite the fact that we know in advance that we can have at best limited knowledge of the complex system and environmental parameters involved? This is an almost philosophical question, and there may be different schools of thought.

One school of thought would claim that there will always reason for doubt on observations, would be reasons that an insight is incomplete or not fully accurate, so we should not not be so sure if @Marcel G can do anything useful with the 8 tanks he has waiting for an experiment? Another perspective would be the farmer in the prehistoric times, who saw that the villagers with plots closer to the river had better yield, and proposed to experiment a bit with water to see if the dryer plots would do better with that. This farmer had no chemistry lab, but observed that water and cow manure helped, so he could produce more food to feed his family.

Some philosophers and natural scientists of the past rejected observations, and they would prefer the logical and philosopical argument as compared to filling the tanks with water and engage in "flawed" experiments and observations. Another school of thought would apply trial and error (we still do that with Monte Carlo simulations on super computers, or in machine learning today), and just apply some value functions to each and every outcome. There is no doubt that some element of trial and error, or discovery with a factor of luck, has brought enormous success in the history of science. Or we could try and optimise our experimental set up so that we aim to optimise the experiments outcome via a logical thought process, which could be called "design of experiment" as the thread's title suggests.

So my key point is that I am not convinced that insisting for the complete set of parameters is necessary or helpful for design of experiment in our hobby. Not especially referring to this thread that has a lot of really good insights, but the argument comes back (rightfully or not) very often on fora and more often than not as an argument to give up on the proposed experiment and continue to follow "common wisdom" or copy other tanks and methods. However in my opinion (this is an opinion and not necessarily the only approach), if we want to make progress in our understanding we can increase both the hit rate and accuracy of experiments by careful preparation, including deciding how observables will be evaluated and supposed to lead to insights.

This discussion is not a new one of course, so I hope for future Artificial Intelligence systems to plow through all data and full tank shots on our fora and tell us what we can learn from it :-)
 
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