Phosphate is the king of the planted tank

dw1305

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Hi all,
Plants evolved from algae... Unfortunately, we cannot go back in time to see the first lakes where plants evolved in and see if they ended up outcompeting the algae
It takes a bit of time to get your head around it, but evolution <"isn't quite like that">. Richard Dawkins <"The Ancestor's Tale"> is a useful read, if you are interested in this area.

Where organisms are related they have a common ancestor (at the nodes, the branching points in the figure). All photosynthetic organisms have a <"common ancestor">, which was a cyanobacteria. That common ancestor is equally related to all the extant photosynthetic organisms.

The ancestor of both the Green Algae and the Plants was an "algae", but it is equally related to all of <"that clade"> that are still extant.

cheers Darrel
 

JoshP12

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Wonderful conversation so far folks.

Here is a question I have: Why do I not have visible algae on my rotala, then. Under my proposed cause, we can simply say that my CO2 concentration is high enough that photorespiration is suppressed and an algal bloom is not triggered - and I am quite satisfied.

However, assume that it is not right, then why do I not have algae smothered on my rotala? It is disintegrating (the new growth "looks nice" on some - although some are thin like tissue paper, but they are getting better daily due to my changes). I ripped up the entire substrate, flooded the tank with ammonia. I have left the tank with 100% lights on, EI level ferts, high CO2, good flow for at least a week and no algae.

I literally uprooted the entire tank prior to this and threw everything out of whack.

Surely, a week of high lights + CO2 + ferts + plants changing themselves AFTER a massive rescape is enough under sub-optimal conditions to bloom algae. Is it not?

Josh

EDIT: surely there is microscopic algae - but I would expect a bloom based on everything that I have done.
 

JoshP12

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Further, part of the reason high light is that much harder is not only because it pushes phosphate consumption (especially under EI conditions, the limitor becomes CO2)- it increases the rate of photolysis; as a result, we oxygenate the water. That O2:CO2 is going to flip the plant from photosynthesis to photorespiration. As a result, our CO2 concentration needs to be higher for two reasons:
1) keep up with the produced ATP and NADPH
2) keep the plant from photorespiration ... as a result, keeping algae at bay (under my assumptions).


This is where the notion that if you turn up light and not CO2, then you will get algae comes from. Unless of course you are riding such high concentrations of CO2 beforehand - in such high light won't do anything (like in my tank ... I never upped my CO2 for 3x a light increase - no adverse effects).
 

dw1305

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Hi all,
The balance of what? We often refer to this enigmatic balance yet no one defines it.
Well we don't really know, we are in <"Donald Rumsfeld territory">.

In terms of <"phosphate availability driving photosynthesis">, I think it does, but only in the same way all that light and all the other nutrients do, you are nearly always going to have a limiting nutrient via Liebig's law (in @Zeus. post). Plant growth is <"like an assembly line">, you need all the components or you don't get a finished "car".

Personally I practice nutrient depletion in the water column, unfortunately what happens in the substrate is a total unknown (for me and <"everyone else">). My only suggestion for the substrate is to leave it relatively undisturbed.

I don't actually know what level I have of any of the plant nutrients in the water column, or which is/are limiting plant growth, but I know I don't have many of any of them because the measure of all ions, the electrical conductivity is low. If I have a conductivity value of 100 microS (~64ppm TDS) I don't have many ions of any description.

Do I have enough nutrients to <"support plant growth?"> I do. How do I know this? <"The plants are growing">.

cheers Darrel
 
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JoshP12

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In terms of <"phosphate availability driving photosynthesis">, I think it does, but only in the same way all that light and all the other nutrients do, you are nearly always going to have a limiting nutrient via Liebig's law (in @Zeus. post). Plant growth is <"like an assembly line">, you need all the components or you don't get a finished "car".
I must be missing something then; if plant growth is an assembly line (i.e. sequential) and photosynthesis (light dependent, then independent) comes first, then it goes:

Light --> Phosphate --> CO2/O2 --> sugar --> the rest.

< Justus von Liebig's Law of the Minimum states that yield is proportional to the amount of the most limiting nutrient, whichever nutrient it may be. >

Every piece up to the limiting nutrient will happen - just like an assembly line. If we consider up to sugar part 1, and the rest part 2, then part 1 dictates part 2.

This would mean that phosphate has a larger impact than Manganese.

We can simply consider the limiting nutrient to be the least in excess. So, yes, there is always a limiting nutrient; however, the driver of those limiting nutrients is photosynthetic rate (whos driver is the light dependent reaction) which plateaus and is directly proportional to available light and phosphate.

What am I missing?

Josh
 

JoshP12

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From < here > @dw1305, we can fathom that what I said is correct and by limiting phosphate we are jamming algae's ability to proceed in the first step - without limiting plants due to their roots.
 

dw1305

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Hi all,
if plant growth is an assembly line (i.e. sequential) and photosynthesis (light dependent, then independent) comes first, then it goes:

Light --> Phosphate --> CO2/O2 --> sugar --> the rest.
That is the point, the rest are equally important. In terms of C3 photosynthesis, and the <"Calvin cycle">, yes, you need phosphate for carbon fixation and energy transfer, but you still need everything else.

This would mean that phosphate has a larger impact than Manganese.
It does, but you still need some manganese (Mn), if you don't have any Mn you don't get a "car".

The most likely nutrients to be deficient are the macronutrients N : P : K, because the plant needs most them. Nitrogen (N) and potassium (K) compounds are nearly all soluble (NO3-, NO2-, NH4+, K+), but things are different for phosphorus (P), many of its compounds are insoluble, so we are interested in both "plant available" phosphorus, and the insoluble reserve, which may become available in certain conditions.
I said is correct and by limiting phosphate we are jamming algae's ability to proceed in the first step - without limiting plants due to their roots.
If you removed all PO4--- ions from the water column, it would stop the growth of phytoplankton & epiphytic and epilithic algae but also of floating plants, mosses, ferns and epiphytic aroids.

Some people might be willing to trade growth of these for a lack of "algae", but I'm not.

cheers Darrel
 

JoshP12

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Hi all, That is the point, the rest are equally important. In terms of C3 photosynthesis, and the <"Calvin cycle">, yes, you need phosphate for carbon fixation and energy transfer, but you still need everything else.

It does, but you still need some manganese (Mn), if you don't have any Mn you don't get a "car".
Thank you Darrel :D. I can appreciate the entire car; however, and I think I am splitting hairs here, if we add a magnitude to the impact each nutrient has on plant growth, then the magnitude of the impact of each nutrient is different. As I think you illustrate when you say:

The most likely nutrients to be deficient are the macronutrients N : P : K, because the plant needs most them. Nitrogen (N) and potassium (K) compounds are nearly all soluble (NO3-, NO2-, NH4+, K+), but things are different for phosphorus (P), many of its compounds are insoluble, so we are interested in both "plant available" phosphorus, and the insoluble reserve, which may become available in certain conditions.If you removed all PO4--- ions from the water column, it would stop the growth of phytoplankton & epiphytic and epilithic algae but also of floating plants, mosses, ferns and epiphytic aroids.
And of the NPK, there has to be an ordering - where I proposed P had the larger impact due to sequence. The variance between them has to exist (or maybe it doesn't and that is where I need to reframe my thinking) and is likely variable on several other factors (i.e. demand) - but does an ordering exist?

Some people might be willing to trade growth of these for a lack of "algae", but I'm not.
Beautiful.

As always, thanks Darrel - much appreciated.

Josh
 

dw1305

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Hi all,
And of the NPK, there has to be an ordering - where I proposed P had the larger impact due to sequence. The variance between them has to exist and is likely variable on several other factors (i.e. demand) - but does an ordering exist?
In terms of sequence it does, in terms of the end result not really.

The first part of the sequence would be the <"light reaction"> where chlorophyll (and accessory pigments) intercept the photons of light.



You can see that iron (Fe), manganese (Mn), sulphur (S) are all required for electron transport. You also have the <"chlorophyll molecules">, with their central magnesium atoms etc.

Chlorophyll a

By charlesy (talk · contribs) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=15164971

cheers Darrel
 

JoshP12

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Hi all, In terms of sequence it does, in terms of the end result not really.

The first part of the sequence would be the <"light reaction"> where chlorophyll (and accessory pigments) intercept the photons of light.



You can see that iron (Fe), manganese (Mn), sulphur (S) are all required for electron transport. You also have the <"chlorophyll molecules">, with their central magnesium atoms etc.

Chlorophyll a

By charlesy (talk · contribs) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=15164971

cheers Darrel
Now, we have to make one assumption - that we are starting with a healthy leaf - FOR, if we did not have carbon to make that healthy leaf, then phosphate is not the king.
I mentioned this though (albeit I did not mention the rest of the nutrients). And so it becomes chicken egg. To develop the tissues required to initiate the first step of the sequence - i.e. build chlorophyll receptor, we require all nutrients.

After establishing the starting point of a healthy chlorophyll, we may be able to attach magnitudes.

To establish this order is ridiculous, however, and impractical.

And it is much better to say that all are equally important.

Hurrah!

:D

Thanks so much Darrel!
 

JoshP12

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Still not entirely sure why my disintegrating rotala does not have algae growing off of it 🤔.

Any ideas?

Josh
 

tiger15

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I am amazed by the depth of discussion resembling Phd dissertation. Most stuff is beyond my grasp as I have never had microbiology and biochemistry beyond elements I learned in general chemistry, biology and environmental engineering. There are more algae species than higher plants, and more factors than algae that can cause outbreak. So attempt to identify one factor, such as phosphate, as a cause of algae is futile. Environmental scientists have long established that excessive nutrients caused algal bloom in natural waters and phosphate is attributed to be the limiting factor. This is why phosphate is now removed from household detergents and lawn fertilizers in US. Tom Barr and EI practitioners have found the opposite though in that insufficient, rather than excessive nutrients, cause algae in aquariums. In his ecologist day job, Tom has come across some eutrophic lakes that have no algae issue, and advised aquarists to focus on growing plants rather than on limiting algae growth. The glass box environment is apparently very different from natural waters, and the algae aquarists have to deal with is also different. So you can discuss as much theories as to what cause algae, there is no simply answer, and ultimately only experimental validation counts.
 
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