Micro from tap water

[dw1305]

Hi all,

unfortunately, practically nobody studies aquarium sediments in this detail,

Perhaps the biggest problem is that you can't earn any money with studies on aquariums.

No, it is a shame <"Could it be the substrate? Tank in terminal decline...">.

Probably the most information on this can be found in the literature on wetland or rice sediments

Perhaps the biggest problem is that you can't earn any money with studies on aquariums. With studies on rice fields, you can at least expect a certain amount of harvest.

Personally, I've lent heavily on <"Rice (Oryza sativa) culture"> and <"constructed wetlands"> (for <"wastewater remediation">) for information.

In an aquatic environment, the acids secreted by the roots would immediately become so diluted that they would not be effective enough.

I think aquatic plants are still altering the composition of the rhizosphere microbiome to facilitate nutrient uptake, basically roots are just leaky structures. Originally the <"Duckweed Index"> actually used an emergent plant <"Why a rooted emergent plant would have been optimal">, rather than a floating one. It had to be a plant with access to atmospheric gases, so "emergent" or "floating" were really the only options.

In addition, aquarium sediments are highly variable. Even when it comes to the substrate, there are practically endless possibilities.

With hind sight having a <"floating plant as my nutrient indicator"> was actually a massive advantage, due to the complex, multifactorial nature of what happens in the substrate. It allowed me to concentrate on the water column and the advantage of that is that every tank has water.

Thus, in flooded sediments, iron and manganese are unlikely to be deficient; rather, they are toxic. Plants counteract this excess by excreting oxygen from their roots.

We have a few posts on <"Radial Oxygen Loss">, you know it is important when you see the root / rhizome architecture of Nelumbo (below) etc. or the Typha sp. in your linked journal* <"Modification of sediment redox potential by three contrasting macrophytes: implications for phosphorus adsorption/desorption">.

This results in the oxidation of the reduced iron (and manganese), which often results in a rusty colour of the roots (called „iron plaque“ => Iron plaque formation on roots of wetland plants).

We've talked about this in terms of iron (Fe) being a two edged sword, with the two "edges" being <"deficiency"> and <"toxicity">.

*Modification of sediment redox potential by three contrasting macrophytes: implications for phosphorus adsorption/desorption

cheers Darrel

 

[Genahanney]

And yet, are trace elements from tap water available to plants?

 

[dw1305]

Hi all,

are trace elements from tap water available to plants?

If they are "ions"? Yes. Whether an ion remains in solution it dependent upon what other ions are in solution, what the pH is etc.

The <"solubility chart"> gives you combinations of ions that are, or aren't, likely to form insoluble compounds.

cheers Darrel

 

[Genahanney]

likely to form insoluble compounds

Can't plants get nutrition from them?
Phosphate with many elements creates insoluble compounds. So, if the soil absorbs phosphates, it turns out that it is saturated with insoluble (inaccessible?) elements that poison the roots of plants?

 

[dw1305]

Hi all,

Can't plants get nutrition from them?

No, only as ions from solution.

... Only ortho-phosphate (monophosphate) is available for plant uptake and algal growth (also known as reactive P because it reacts with ammonium molybdate in the main analytical method employed for phosphate).....

Phosphate with many elements creates insoluble compounds.

It does. Scientists tend to look at both plant available (ortho)phosphate (PO4---) and also the potential reservoir <"Limited amount of total phosphorus actually feeds algae, study finds - Lake Scientist"> of insoluble phosphorus (P) compounds <"https://www.sciencedirect.com/science/article/pii/S0048969722041110">. The transformation from insoluble to soluble is usually mediated by micro-organisms (Phosphate solubilizing microorganisms (PSMs) <"https://www.sciencedirect.com/science/article/pii/S0045653524001693">).

So, if the soil absorbs phosphates, it turns out that it is saturated with insoluble (inaccessible?) elements that poison the roots of plants?

If it is insoluble it is inaccessible and won't poison anything, it is the <"brick analogy"> for iron (Fe)

It is back to the <"red house brick analogy">, you can call it iron rich (which is true, it is red), but none of that iron is plant available. You can add as much iron as you like, but if it isn't plant available? It is the same as not adding any.

An insoluble phosphate compound, in the substrate, could become available in the reducing conditions that @Marcel G mentioned earlier in the thread.

Phosphorus is a bit of a strange element, in that both low and high pH values favour the formation of insoluble compounds. Under acidic conditions aluminium (Al) and iron (Fe) phosphates form and in alkaline conditions calcium (Ca) phosphate. Around pH6 - pH7 you get H₂PO₄ - ions and they are more plant available than the HPO₄-- ions found above pH7.

cheers Darrel

 

[Genahanney]

Превращение нерастворимых веществ в растворимые обычно происходит с помощью микроорганизмов (фосфатредуцирующих микроорганизмов (PSM) https://www.sciencedirect.com/science/article/pii/S0045653524001693).

I wonder how likely they are to occur in an aquarium?
It turns out that at a pH of 5.5 (or less), phosphate becomes inaccessible to plants?

 

[dw1305]

Hi all,

I wonder how likely they are to occur in an aquarium?

I'm pretty certain they will occur if / once the sediment matures. I think, for microbes, it is always the <"Field of Dreams"> analogy.

"If you build it, they will come."

<"Journal - Oase Scaperline 60 Reef Tank">.

cheers Darrel

 

[Genahanney]

Hi all,

I'm pretty certain they will occur if / once the sediment matures. I think, for microbes, it is always the <"Field of Dreams"> analogy.

<"Journal - Oase Scaperline 60 Reef Tank">.

cheers Darrel

It turns out that at a pH of 5.5 (or less), phosphate becomes inaccessible to plants?

 

[MichaelJ]

It turns out that at a pH of 5.5 (or less), phosphate becomes inaccessible to plants?

This might help:



Cheers,
Michael

 

[Happi]

Hello. It is believed that micros are already present in tap water. Most likely it is, but aren't there oxidized elements? Are they available to plants? Do I understand correctly that they do the restoration of elements using root cilias? Thank you a lot.

In hard water with a high pH, many trace elements including Fe are often precipitated, making them less available to the plants. The high pH can cause certain nutrients to form insoluble compounds that are not easily absorbed by the plants . Additionally, in oxygen-rich environments, many of these elements, especially metals like iron or manganese, are prone to oxidation, further reducing their availability to plants. However, in more acidic conditions, particularly when carbon dioxide (CO2) is present, these elements become more soluble. The acidity helps to break down the precipitates, releasing these nutrients back into a form that plants can absorb. This is why the pH of water and the presence of CO2 can significantly affect nutrient availability, making them more accessible to plants in an acidic environment.

Furthermore, It is true that in oxygenated aquarium water, many nutrients become precipitated and are rendered unavailable to plants. These nutrients eventually settle into the substrate, where they may remain in their precipitated form unless the pH of water/substrate becomes more acidic. In such cases, these precipitated elements will start to dissolve again. Conversely, if the pH or alkalinity of the water increases, they will revert to their precipitated form. Depending on the accumulation of these nutrients in both the water and substrate, they can become highly toxic, particularly elements like iron (Fe) and other heavy trace metals.

In the substrate, various factors, such as chelation, can help protect plants from nutrient toxicity by binding the elements in a form that is less harmful to them. However, the risk of toxicity remains a concern, especially if the concentration of reduced elements becomes too high. This is one of the primary reasons I advise caution when adding root tabs that are rich in iron and micronutrients.

To answer your main question, yes, many micronutrients are already present in the tap water. However, it's important to consider how they might behave in the aquarium. You could enhance their availability and reduce their toxicity by adding chelating agents like EDTA or DTPA to the water.

 

[Happi]

It turns out that at a pH of 5.5 (or less), phosphate becomes inaccessible to plants?

This might help:

View attachment 225033

Cheers,
Michael

phosphate becoming inaccessible at a pH of 5.5 is not true for aquariums. In fact, in an aquarium, phosphate is highly soluble and available to plants even at pH 5.5. This difference arises from how phosphate interacts with the environment (soil vs water), and in an aquarium, the conditions do not promote the same insoluble compounds that would render phosphate inaccessible to plants.

The Moulder's chart, while useful for understanding nutrient availability in soil, should be taken with a grain of salt when applied to aquariums. This is because the chemistry of water is fundamentally different from soil.

 

[Connswater]

Hi all,

If they are "ions"? Yes. Whether an ion remains in solution it dependent upon what other ions are in solution, what the pH is etc.

The <"solubility chart"> gives you combinations of ions that are, or aren't, likely to form insoluble compounds.

cheers Darrel

A little bit of an explanation Darrel for the less chemistry minded might help, I think I know what it is showing but I'm not totally sure.

 

[Connswater]

This might help:

View attachment 225033

Cheers,
Michael

Silly me, this is very helpful, have seen what I missed.

 

[dw1305]

Hi all,

...... In hard water with a high pH, many trace elements including Fe are often precipitated, making them less available to the plants. The high pH can cause certain nutrients to form insoluble compounds that are not easily absorbed by the plants ......

That is the perfect answer, concise, complete and comprehensible. I've now got "Post Envy" to go with <"Frogbit Envy">.

I think I know what it is showing but I'm not totally sure.

Easy enough, if you have ions in solution they will combine to form insoluble compounds wherever there is a green "insoluble" square.

If you have a "choice" of insoluble compounds? They will come out of solution in relation to their solubilities, least soluble first, via the <"common ion effect">.

As an example all potassium (K) compounds are soluble, and so are all nitrate (NO3) ones. If you add the salt potassium nitrate (KNO3) to water, it will dissolve into K+ and NO3- ions and those ions will remain in solution (and plant available) whatever other compounds you add. The compound KNO3 will only reform if we exceed the solubility limit, exactly the same as it is for "sea salt" sodium chloride (NaCl).

However it becomes a bit more complicated if we have a salt like "Epsom Salts", magnesium sulphate heptahydrate (MgSO4.7H2O), fine on its own it forms magnesium ions (Mg++) and sulphate ions (SO4--), but both cation and anion will combine to form insoluble salts, like magnesium phosphate ((Mg(H2PO4)2).nH2O) or (sparingly soluble) calcium sulphate (CaSO4.nH2O).

This is why we usually dry dose salts that raise dGH and don't have calcium (Ca) added to "All in One" fertiliser mixes.

cheers Darrel

 

[Happi]

A little bit of an explanation Darrel for the less chemistry minded might help, I think I know what it is showing but I'm not totally sure.

Using PO4 as an example, Here’s the catch, though: while this chart is accurate as far as solubility goes, it doesn’t highlight that adding chelating agents or lowering the pH can alter the solubility of phosphates with certain metals. The solubility of phosphate salts is indeed influenced by factors like pH and the presence of chelating agents, which can bind to metal ions and prevent them from precipitating as insoluble phosphates. The same principle applies to many other chemicals or elements listed.

 

[MichaelJ]

Using PO4 as an example, Here’s the catch, though: while this chart is accurate as far as solubility goes, it doesn’t highlight that adding chelating agents or lowering the pH can alter the solubility of phosphates with certain metals. The solubility of phosphate salts is indeed influenced by factors like pH and the presence of chelating agents, which can bind to metal ions and prevent them from precipitating as insoluble phosphates. The same principle applies to many other chemicals or elements listed.

True. pH is a factor and so is the amount you're actually trying to dissolve relative to the body of water. I am using both CaSO4 and CaCO3 in my tanks. The amounts I am using combined with my relatively low pH makes both perfectly fine and soluble.

Cheers,
Michael

 

[dw1305]

Hi all,

The solubility of phosphate salts is indeed influenced by factors like pH and the presence of chelating agents, which can bind to metal ions and prevent them from precipitating as insoluble phosphates

You can actually buy <"phosphate fertilisers"> as <"chelates">, I'm pretty sure it is never necessary for us.

I don't see phosphate deficiency as a big problem, particularly as its highly mobile within the plant.

cheers Darrel

 

[MichaelJ]

But thanks Michael, I was thinking of printing this out and laminating it,

As @Happi said above; take the chart with a grain of salt. The Moulder chart really applies to soil.

Cheers,
Michael

 

[Genahanney]

Кроме того, в насыщенной кислородом аквариумной воде многие питательные вещества выпадают в осадок и становятся недоступными для растений. Эти питательные вещества в конечном итоге оседают на субстрате, где они могут оставаться в осаждённой форме, пока pH воды/субстрата не станет более кислым.

Однако риск токсичности по-прежнему вызывает беспокойство, особенно если концентрация восстановленных элементов становится слишком высокой

So all trace elements from tap water (except iron) are available to plants at pH 6.5?
What factors influence recovery reactions?)

 

[Happi]

You can actually buy <"phosphate fertilisers"> as <"chelates">, I'm pretty sure it is never necessary for us.

I'm curious about the chelation methods used for this product and the other products on the website. I assume they use Amino based Chelation?