Micro from tap water

[Genahanney]

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.

 

[hypnogogia]

Can you access a water report to see what’s in your tap water?

 

[Connswater]

micros are already present in tap water.

Many certainly are. Copper for example.

If your tap water is soft you may be fine.

In terms of the garden, if you try to grow acid loving plants in even mildly alkaline soil you will need to use some commercial micro fertiliser, chelated Iron. If your tap water is hard, pouring hard tap water over the soil without a chelated product will not cure chlorosis.

Yellow dying plants are common in tropical fish shops in hard water areas. Though lack of CO2 is often why plants are dead or dying in shops - and dried out after being far to long in the hermetically sealed packs, past any use by date, not that a sell by date is ever on the package.

Many, but not all, aquatic plants are lime haters, to use a gardening layman's term. Thus in an aquarium with even moderately hard water I find it hard to imagine that the tap water will provide the micro nutrients in sufficient amounts. I have, however, certainly successfully run hard water tanks with little other than a pond soil and silver sand base and the addition of magnesium and manganese with iron and of course fish food, via the fish to deliver macro nutrients. But, with CO2 and intense lighting I do find I sometimes have to add macro nutrients and I play safe and add a balanced amount of micro nutrients. I also, tend to add extra Potassium, which I know, is a macro nutrient.

 

[ElleDee]

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.

It depends on the element. Iron is always at the top of the list when you are talking micro deficiencies, not because there isn't iron in the tank, but that it's often not in an available form.

Yes, root hairs can modulate the soil that immediately surrounds them to increase availability of various nutrients, but some species are better at scavenging than others. Also root hairs are very fragile and are easily disrupted, so if you replant or move things around a lot they won't be able to function as intended.

 

[Genahanney]

Can you access a water report to see what’s in your tap water?

Yes, when I need I can to do ICP-test for that goal.

 

[Genahanney]

Many certainly are. Copper for example.

If your tap water is soft you may be fine.

In terms of the garden, if you try to grow acid loving plants in even mildly alkaline soil you will need to use some commercial micro fertiliser, chelated Iron. If your tap water is hard, pouring hard tap water over the soil without a chelated product will not cure chlorosis.

Yellow dying plants are common in tropical fish shops in hard water areas. Though lack of CO2 is often why plants are dead or dying in shops - and dried out after being far to long in the hermetically sealed packs, past any use by date, not a sell by date is ever on the package.

Many, but not all, aquatic plants are lime haters, to use a gardening layman's term. Thus in an aquarium with even moderately hard water I find it hard to imagine that the tap water will provide the micro nutrients in sufficient amounts. I have, however, certainly successfully run tanks with little other than a pond soil and silver sand base and the addition of magnesium and manganese with iron and of course fish food, via the fish to deliver macro nutrients. But, with CO2 and intense lighting I do find I sometimes have to add macro nutrients and I play safe and add a balanced amount of micro nutrients. I also, tend to add extra Potassium, which I know, is a macro nutrient.

But when we use CO2, the water becomes softer, does it mean that the availability of elements becomes higher? I want to understand, is the process of oxidation of trace elements final or can plants use them? If so, how does their recovery work?

 

[Genahanney]

Yes, root hairs can modulate the soil that immediately surrounds them to increase availability of various nutrients, but some species are better at scavenging than others. Also root hairs are very fragile and are easily disrupted, so if you replant or move things around a lot they won't be able to function as intended.

I would like to understand exactly which elements can be restored, how this whole process takes place..

 

[Genahanney]

And there is another question: when iron forms an insoluble precipitate with phosphate, can plants consume phosphates from it? And what is done with the rest of the iron?

 

[Connswater]

But when we use CO2, the water becomes softer, does it mean that the availability of elements becomes higher? I want to understand, is the process of oxidation of trace elements final or can plants use them? If so, how does their recovery work?

The pH does temporarily come down, yes but the TDS isn't affected. And that is what affects availability of Iron. Beyond this point of understanding my chemistry is not likely to be adequate, over to someone more scientific. I do know that microbes, plant roots and substrates may in certain circumstances ca be of assistance to unbind certain elements but the process and the likelihood in an aquarium is beyond me. But a good question.

 

[ElleDee]

I would like to understand exactly which elements can be restored, how this whole process takes place..

As I said before here, the main micro you need to worry about here is iron. At the ph values most of us run our tanks at (around neutral to somewhat acidic) nutrient availability it not a huge issue for the other micros (or they are needed in such small amounts that it doesn't make a practical difference). Do you think you are having an issue with availability?

As for how the roots work, they can excrete acids that change the pH of the adjacent soil, and they have ways of encouraging beneficial bacteria and fungi that mediate nutrients uptake. Do I remember what those ways are specifically? No, I do not. 🙃

Is your goal with this thread to understand plant nutrient uptake or to make sure that your plants are getting what they need? If it's the former, I'd seek out actual educational resources for plant biology because it's an involved topic. If it's the latter, understanding your specific situation will be more helpful in identifying and remedying specific problems.

 

[dw1305]

Hi all,

And there is another question: when iron forms an insoluble precipitate with phosphate, can plants consume phosphates from it? And what is done with the rest of the iron?

Usually <"you run out of iron (Fe++(+)) ions"> before you run out of phosphate (PO4---) ions, but in alkaline conditions iron forms a lot of insoluble compounds <"My first adventure into aquascaping - Aquael 125L Walstad">.

As I said before here, the main micro you need to worry about here is iron. At the ph values most of us run our tanks at (around neutral to somewhat acidic) nutrient availability it not a huge issue for the other micros (or they are needed in such small amounts that it doesn't make a practical difference).

That one.

As for how the roots work, they can excrete acids that change the pH of the adjacent soil, and they have ways of encouraging beneficial bacteria and fungi that mediate nutrients uptake.

Siderophores <"Amazon Frogbit (Limnobium laevigatum) phytoremediation references">.

Is your goal with this thread to understand plant nutrient uptake or to make sure that your plants are getting what they need? If it's the former, I'd seek out actual educational resources for plant biology because it's an involved topic. If it's the latter, understanding your specific situation will be more helpful in identifying and remedying specific problems.

Perfect summary, @Genahanney have a look at <"What is the “Duckweed Index” all about?"> and subsequent posts.

cheers Darrel

 

[Connswater]

As I said before here, the main micro you need to worry about here is iron. At the ph values most of us run our tanks at (around neutral to somewhat acidic) nutrient availability it not a huge issue for the other micros (or they are needed in such small amounts that it doesn't make a practical difference). Do you think you are having an issue with availability?

As for how the roots work, they can excrete acids that change the pH of the adjacent soil, and they have ways of encouraging beneficial bacteria and fungi that mediate nutrients uptake. Do I remember what those ways are specifically? No, I do not. 🙃

Is your goal with this thread to understand plant nutrient uptake or to make sure that your plants are getting what they need? If it's the former, I'd seek out actual educational resources for plant biology because it's an involved topic. If it's the latter, understanding your specific situation will be more helpful in identifying and remedying specific problems.

My chemistry PhD friend and polymer science industrial team leader, admits quite cheerfully to me, he doesn't fully understand the water chemistry, micro nutrients, impact of CO2 injection on plant nutrient uptake, he hasn't he tells me the biology/botany to fully talk me through the complexities, he does say, your plants look healthy and yes, chelated Iron and hardwater, good idea.

 

[dw1305]

Hi all,

admits quite cheerfully to me, he doesn't fully understand the water chemistry, micro nutrients, impact of CO2 injection on plant nutrient uptake, he hasn't he tells me the biology/botany to fully talk me through the complexities

I'm going to guess that the number of people who really fully understand all the complexities is pretty small, due the <"complex multifactorial nature"> of those interactions. I certainly don't, it is all fuzzy <"shades of grey"> for me.

A lot of researchers work on non-rooted aquatic plants <"https://academic.oup.com/aobpla/article/15/4/plad026/7189803">, just because that <"takes the substrate out of the equation">.

he does say, your plants look healthy

So this is the one that counts, if you want to give it a scientific name? It is a <"bioassay">.

How do I know I'm dosing enough for my plants and what's too much?

Just use <"plant growth">, it works and it is actually a technique (<"bioassay">) used by a lot of scientists.

and yes, chelated Iron and hardwater, good idea.

We have a thread <"Cloudy Water Hazy Water and Algae!">, with "before" and "after" pictures:

I hope showing this helps. This was my tank at its worse before the iron deficiency was diagnosed and sorted, everything was dying:

and this was it after dosing iron. Note: I had to take the seiryu stone out, and that reduced the hardness a bit.

cheers Darrel

 

[Connswater]

We have a thread <"Cloudy Water Hazy Water and Algae!">, with "before" and "after" pictures:

The before and after pictures are simply eyeopeners. Great stuff.

 

[dw1305]

Hi all,

The before and after pictures are simply eyeopeners.

<"They certainly are">. I really have to thank @keef321 for them. Keith originally contacted me via PM (below)

• First the most important one, when plants are iron deficient the <"Duckweed Index" doesn't work">.”

...... Is there any chance of you thinking about re-wording this, as it makes it sounds like you cannot use the index to help with iron deficient plants? Please do not be offended by my suggestion, I was helped so much by your index, and simply want others to realise it can help them with iron 😀 I used the duckweed index to a great extent to help me diagnose iron deficiency, as without the chelated iron the duckweed simply melted away, and as i moved over to stronger & stronger chelates it improved lots ......

And it would be fair to say that I certainly wasn't offended, in fact quite the opposite, the improvement was better than I could have ever imagined and that is why I patched them into <"What is the “Duckweed Index” all about?">

..... it is absolutely fantastic. I tell people about Liebig's limiting nutrient, but the transformation in your tank is better than I could have ever imagined.

Even I'm amazed by that. It is <"Frogbit Envy"> all <"over again">. That noise you can hear (wherever you are) is me throwing <"my toys out of the pram again">.

cheers Darrel

 

[Marcel G]

As for how the roots work, they can excrete acids that change the pH of the adjacent soil, and they have ways of encouraging beneficial bacteria and fungi that mediate nutrients uptake ...

Here I would beg to differ slightly. What @ElleDee writes is true for terrestrial plants, but apparently not for aquatic plants. In an aquatic environment, the acids secreted by the roots would immediately become so diluted that they would not be effective enough. Flooded sediments generally have a very low redox (as low as -150 mV at a depth of 2 cm, and even -250 mV at 10 cm - see https://doi.org/10.1071/MF02087). With such a low redox, the oxidised iron and manganese are rapidly and abundantly reduced and thus transferred back into the soil solution, where they are available to plants. Not only that, but the iron and manganese in this soil solution can be so high as a result of this reduction that plants are often at risk of poisoning (toxicity). 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. 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).

 

[Connswater]

Here I would beg to differ slightly. What @ElleDee writes is true for terrestrial plants, but apparently not for aquatic plants. In an aquatic environment, the acids secreted by the roots would immediately become so diluted that they would not be effective enough. Flooded sediments generally have a very low redox (as low as -150 mV at a depth of 2 cm, and even -250 mV at 10 cm - see Modification of sediment redox potential by three contrasting macrophytes: implications for phosphorus adsorption/desorption). With such a low redox, the oxidised iron and manganese are rapidly and abundantly reduced and thus transferred back into the soil solution, where they are available to plants. Not only that, but the iron and manganese in this soil solution can be so high as a result of this reduction that plants are often at risk of poisoning (toxicity). 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. 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).

Very interesting, many thanks for that.
Does the hardness of the water affect the chemical process of reduction? I have always had to use sequestered Iron in very hard water. And in terms of substrate, does it make a big difference if the substrate is inert - say fine gravel, or horticultural grit or play pit sand? Fish waste does not seem to significantly move through my substrate, I believe my high filtration levels largely prevent this, I have little mulm but don't vacuum the substrate.
Following your post, and trying to think back, I suspect I have had to use less chelated Iron when my tanks have had a couple of inches of humus rich soil compared to neutral material. I also experimented with a tank half soil under sand and half not, the crypts made strenuous efforts to get roots to the soil, other plants seemed less 'attracted' to the bank of humus rich material.
But then, I complicate things now by using no soil but soften (or try to, I am often short of soft water in the summer) my main tank water down from a KH of around 16 to 8.

 

[Marcel G]

As I understand it, while in aquarium water mostly oxidation reactions take place (because the plants in a densely planted aquarium maintain high oxygen levels => so the water is highly oxygenated, with redox normally around +400 mV), in organic sediment it is the opposite. There, within a few hours after the substrate has been flooded with water, the aerobic bacteria will drain all available oxygen and die, and anaerobic bacteria will take their place, which will start to reduce rather than oxidize the surrounding substances. There may still be aerobic bacteria in the top layer of the substrate (to a depth of about 0.5 cm), because some oxygen from the water still gets there by diffusion. The lower down, however, the more the substrate will be dominated by various strongly reduced compounds => of the minerals there are mainly reduced phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), molybdenum (Mo) and silicon (Si), and of the gases mainly carbon dioxide (CO2), methane (CH4), nitrogen (N2), hydrogen (H2) or hydrogen sulphide (H2S). Conversely, the availability of substances such as zinc (Zn), copper (Cu) and sulphur (S) is reportedly decreasing. The amount and percentage of these substances is likely to depend most on the mineral composition of the substrate and on the microbial composition and organic content. In any case, the concentrations of such dissolved nutrients in the substrate may be several orders of magnitude higher than those in the water column. To give you an idea: In one scientific study, they measured Fe2+ concentrations at the sediment-water column boundary of 0.55 ppm, at 5 cm depth around 2.8 ppm, and at 35 cm depth a hard-to-believe 22 ppm. So, if I were to summarize, it seems to me that while in the heavily oxygenated water column of our aquariums, the plants struggle more with phosphorus and iron/manganese deficiency, in the organic substrate they struggle with their toxicity. In inert sand (where there is not much detritus), the situation is probably a little different, as the bacteria will lack organic compounds from which to extract and convert (reduce) these substances. Of course, when plants are transplanted or the substrate is otherwise disturbed, the whole redox cascade will be disrupted and a lot of those reduced substances will leach into the water column (where they will probably oxidize very quickly). Finally, I would like to point out that I am not an expert on these things. So I am describing it as I understand it from reading the literature. If I am wrong about anything, I apologize. Everyone is of course free to check or study this in more detail. Probably the most information on this can be found in the literature on wetland or rice sediments (unfortunately, practically nobody studies aquarium sediments in this detail, as far as I know).

 

[Teleos]

Probably the most information on this can be found in the literature on wetland or rice sediments (unfortunately, practically nobody studies aquarium sediments in this detail, as far as I know).

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

 

[Marcel G]

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

I agree, it is possible that the redox will be higher in aquarium substrates that are not as fine and choked as mud natural sediments. Unfortunately, until someone measures it, all our thoughts will be mere speculation. The only more reliable indicator may be that „iron plaque“ on the roots => if you see it, you can be sure that iron reduction is actually occurring in your substrate (i.e. that the plants there are dealing with potential toxicity of iron). On the other hand, most Japanese substrates partially break down into fine mud in water over time. Thus, low redox is to be expected there. I don't know what lesson to take from this for our aquariums. I just wanted to point out this difference between the water column and the sediment, because I think it's good to know about it.