No problem Darrel, according to my water report my water contains <3 ug/l manganese? I think this equates to 0.003ppm, but my maths isn’t the best 😛
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Plant deficiencies and the Fe Experiment
- Thread starter KirstyF
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John q
Member
My suspicion is that Mn edta is far more stable in higher ph than Fe edta is, but that's just a hunch based on a few bread crumbs of info I've seen.
One study suggests at a ph of 9 80% of the Mn remained in solution.
"The percentage of Mn that remains in solution after 3 days of interaction at pH range 6–11 is shown in Figure 3. Up to 80% of Mn remains in solution until pH= 8 in all the treatments. Above this pH, Mn starts to precipitate in treatments with HEEDTA and IDHA while for EDTA and
EDDS Mn remain in solution until pH=9. At a pH of 10, around 40% of Mn is maintained in solution in treatments with EDTA, EDDS, HEEDTA and IDHA. Treatments with DTPA and o,p-EDDHA maintain more Mn in solution at the highest pHs, keeping around 80% of Mn in solution at pH 10."
Source:
The other morsels of info come via Solufeed and Royal Brinkman, and there descriptions of Mn 13% edta.
"Easygro Mn-EDTA 13% can be used to prevent a shortage of manganese. It is of high importance to always add the right dosage to the crop in order to prevent a deficiency as well as a shortage of this nutrient.
The manganese chelate remains stable and thus available to the plant, in a pH range from 5-9."
And Solufeed:
"Composition
A spray agglomerated microgranule formulation of manganese ethylenediamine tetraacetate (Mn EDTA) containing:
Water soluble Mn: 13%
Mn chelated by EDTA: min 12.5%
Practical pH stability range: 4 – 9 (in aqueous solution)."
So no hard facts I'm afraid, just my musings. Would love to hear the thoughts of @_Maq_ or @X3NiTH on this.
_Maq_
Member
Well, coordination chemistry is a higher-grade field and I do not dare to share my amateurish thoughts on this. Next to that, I do not care much for artificial chelating agents because I've learned to live without them.
I can contribute only some side-remarks.
Plants take up Mn(II) ions. In the water column, bivalent manganese gets oxidized to Mn(III) - still mostly soluble - and then to Mn(IV), generally in the form of insoluble MnO2. Just like iron, except that the oxidation runs at slower pace. Therefore, manganese remains accessible for much longer time. In most circumstances.
MnO2 may get reduced in the sediment just like Fe(OH)3 and other iron compounds, and this is the way plants obtain most of both metals in natural conditions.
Iron and manganese are in competing relationship when taken up by plants. That means, excess of one may hinder uptake of the other. I don't know if this is ever relevant in our tanks. In nature, concentrations of dissolved iron are often by an order or even more lower than concentration of dissolved manganese (and often other transition metals as well) despite the fact that iron per se is regularly present in vastly larger amounts. In light of that, I assume that manganese deficiency induced by dissolved iron is possible in our tanks, after all, esp. when overdosing chelated iron. Of course, I don't know for sure.
In nature, acquiring iron regularly requires much more sophisticated effort from the plants than acquiring other transition metals. Cohabitation with soil microbes (in the rhizosphere) is often essential. I believe something similar may occur in the roots of floating plants as well. We often see "iron-rich" waters, but that usually means that the iron is not truly dissolved but oxidized and present in nanoparticles. These particles may get trapped on the surface of the roots of floating plants, and reduced/dissolved by the plants themselves (by exuding simple aliphatic acids, par example) or by microbes by so called siderophores.
In general, nature is full of natural chelators. Many common organic compounds can form complexes with metals. Also, particulate organic matter (detritus) acts as an adsorbent of transition metals and their compounds. Such a connection is attractive for microbes which can dissolve and utilize them. In the end, plants benefit from it, too. (That is not to say that we want the share of organic matter in the substrate higher than units of per cent.)
The only ground for using chelated micronutrients as fertilizers is therefore our desire to keep plants in conditions where their natural abilities in acquiring these metals are not sufficient. Very often it's the case of high pH and/or highly alkaline (rich in bicarbonates) environment. Some plants (and farmers' crops!) can't handle it without our artificial help.
I suspect that CO2 injection makes the issue more pronounced, or at least more murky, because CO2 injection enables pH decrease without concomitant alkalinity drop. That seems to be the reason that Tonina is generally considered demanding species, while it grows like a weed in all my tanks. I don't inject CO2, so I must keep alkalinity truly low to get into acidic range.
Thanks for that information @John q . My PH is around =>8, so it looks like EDTA Mn should suffice. I have ordered some to try it out.
I did not realise that there was a competing relationship with Iron @_Maq_ so thank you for bringing that to my attention. Now I know this I may make some adjustments in my Iron dosing. I am thinking of making my own EI mix from dry ferts at some point, as this may allow me to control my Macro & Micro levels better, rather than using an AIO fert and then adding Iron etc.
Thank you all for your help 🙂 and your detailed responses.
I did not realise that there was a competing relationship with Iron @_Maq_ so thank you for bringing that to my attention. Now I know this I may make some adjustments in my Iron dosing. I am thinking of making my own EI mix from dry ferts at some point, as this may allow me to control my Macro & Micro levels better, rather than using an AIO fert and then adding Iron etc.
Thank you all for your help 🙂 and your detailed responses.
_Maq_
Member
My conditions are different, yet some cautionary principles are valid. Par example, iron should not be dosed together with phosphorus.
In low-tech, I'm far from fertilizing daily. So, when dosing iron I do not dose anything else a few days before and after. Even if you dose chelated iron, I assume it disappears from the water column within a couple of days. After that, it should not hinder uptake of other nutrients because all iron present remains in insoluble form and plants get it only when employing active measures (dissolving it through root exudation of organic acids).
So I have got my 13% Manganese. With a daily dose of 1ml, container volume 1000ml, dosing frequency 3 times a week, and a week target of 0.04ppm, the IFC fert calculator for me 60l tank comes out at 6.15g. Perfect a teaspoon. I think this is correct, fingers crossed 🧐
@Hufsa I hope you dont mind me asking, but I noticed looking at one of your threads, you mention a fe:mn ratio of 2:1, so I thought I would start of low and build up and see what results I get. Is this still your experience? My fe dosing is a bit on the high side (due to using an all in one fert + DTPA + EDDHA + sechem iron), but I thought I can always double the mn dose if I dont see a result.
Im starting to think I might just follow the footsteps of @dw1305 and mix in some rain water or RO, to bring down my hardness, it might be easier than battling with iron issues etc, due to hardness. My only thing is it doesnt rain too much here, so I might have to make RO, but if Im only doing 50% mix, even in my future planned tank of 180 liters, with a 50% water change, its still only 45 litres.
@Hufsa I hope you dont mind me asking, but I noticed looking at one of your threads, you mention a fe:mn ratio of 2:1, so I thought I would start of low and build up and see what results I get. Is this still your experience? My fe dosing is a bit on the high side (due to using an all in one fert + DTPA + EDDHA + sechem iron), but I thought I can always double the mn dose if I dont see a result.
Im starting to think I might just follow the footsteps of @dw1305 and mix in some rain water or RO, to bring down my hardness, it might be easier than battling with iron issues etc, due to hardness. My only thing is it doesnt rain too much here, so I might have to make RO, but if Im only doing 50% mix, even in my future planned tank of 180 liters, with a 50% water change, its still only 45 litres.
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_Maq_
Member
This is the ratio of uptake by the plants. Yet since iron is much more difficult to acquire (losses are substantial), it is often necessary to dose more iron. Par example Fe:Mn = 4:1. Generally, iron is a very special case among nutrients.
Highly recommended, ever.
Thought I would give an update on progress. I continued with my dosing of DTPA, EDDHA & Seachem iron and added the Manganese. I got positive results from adding the Manganese, with a positive increase in plant health and greening. So in conclusion now trying out various chelates etc, I have found the best mix from my expereince is DTPA, EDDHA, Seachem iron and Manganese, provides the best results. Obviously this was not carried out in laboratory conditions, and other variables may be at play, but I can remove a chelate and clearly see the iron deficiency return.
I have since moved over to a 50% RO / 50% Tap Water mix, that has reduced my KH to a target level of 4. Due to the mechanics of water chemistry, the PH is only reduced (I am told be experts on this forum, this will only be a 0.2PH change) a small amount =<0.2PH. My plants have much better form, and I have reduced my iron mix dosing by 50%. I did notice after doing this the Frogbit (Duckweed index) appeared less green, and started to get eaten by my shrimp. This I think was the first sign of iron deficiency creeping in again. I have also noticed the Hygrophila Pinnatifida started to get pinholes in all of it's leaves, and now some of them have gone white, again, in my experience could be iron deficiency. I will bring up the iron dose levels and see if things improve. If this is indeed iron deficiency, then one can see how the high PH still causes issues.
I have since moved over to a 50% RO / 50% Tap Water mix, that has reduced my KH to a target level of 4. Due to the mechanics of water chemistry, the PH is only reduced (I am told be experts on this forum, this will only be a 0.2PH change) a small amount =<0.2PH. My plants have much better form, and I have reduced my iron mix dosing by 50%. I did notice after doing this the Frogbit (Duckweed index) appeared less green, and started to get eaten by my shrimp. This I think was the first sign of iron deficiency creeping in again. I have also noticed the Hygrophila Pinnatifida started to get pinholes in all of it's leaves, and now some of them have gone white, again, in my experience could be iron deficiency. I will bring up the iron dose levels and see if things improve. If this is indeed iron deficiency, then one can see how the high PH still causes issues.
_Maq_
Member
From my point, it is still sky high.
Agreed, I don’t see the point in running an RO system, to then keep the carbonates so high. A dash of tap water at best, not 50%, would bring the KH down to a worthwhile level.
But, what ppm were the daily/weekly target for each of these DTPA, EDDHA & Seachem Iron, Mn ? was Mn chelated?
if you can already provide RO water to your setup, I would suggest going 100% RO and Mineralize it with needed Minerals and Nutrients.
Thank you for your feedback and interesting advice. I went for 50% Tap / Water for the following reasons:
1) I thought 50% would be a happy medium, as it easy to judge the mix (I directly mix this in the tank).
2) I do not need to store much RODI water. In my 60litre tank I only need 15 litres per water change.
3) The Dennis Wong website (always seems to offer good information) states between 2-7 dkh you can keep 97% of commercial aquatic plants in optimal condition, so I thought KH 4 woule be a good target.
4) Green Aqua recommends remineralising to 150ppm, equating to approx GH 8, KH 4.
5) Future plans are to eventually have a 90P (180 litres), and as I can store 100 litres in my living space, this seemed possible with 50% RODI / 50% TAP.
The benefits so far of the 50% mix, is I can finally grow Rotala species 🙂 (only tried one so far though, still early days), better health of plants overall (so far), with the negative being I will still potentially battle against some iron issues due to high PH / alkilinity. I will be honest, that I thought the iron would be more available to the plants with this mix, but thats why we do these tests and learn 🙂
I am now thinking after viewing a 90P that it might be a bit large for my living space, and either a 75P (120-130ish litres), or a deeper 60P 45 (90 litres) would be better. I am pretty short at around 5ft5, and the WIO 75P is available only 40cm high tank, and 60P 45 only 36 high, so this is also attractive, as it makes maintenance easier. Although I might see if I can see an ADA 75P in person which as 45cm high, to see if I can get away with this, as it looks the best dimensions to my eyes.
Anyway, with say a 75P, then a 50% water change with RODI would only be 65 litres, so this does sound achieavable.
I would be interested to know your thoughts on why 4KH is still considered high, and what a worhwhile KH level is, and potential benefits. I would have to bring up GH a bit for Amano & cherry shrimp. Thank you for your input to this topic 🙂
_Maq_
Member
I'm far from an expert, but I still somehow believe that both the snails and shrimps can satisfy their needs from their food, and thus don't need high calcium content in the water. True, some of these invertebrates hate acidic water. But there is no intrinsic correlation between higher pH and calcium content. A water can be basic while low in Ca, and vice versa. Not typical, but possible.
I may be wrong, I fully admit.
I've read some number of scientific books on plants and their nutrition and I have never encountered any positive mention about bicarbonates. Meaning, some plants tolerate it, other hate it, but none like it.
Excuse me that I've failed to keep in mind whether you inject CO2 or not. If yes, then there's perhaps one good reason to maintain alkalinity about 2 °dKH. If it's lower and you inject some 30 mg/L CO2, you could push pH lower than you like. Still, I suspect that some species struggle in such conditions - meaning acidic pH with non-zero alkalinity. (That suggests that decreasing both CO2 injection and bicarbonate content could lead to better results, but... everybody seems to pray to 30 mg/L.)
If you don't inject CO2, you certainly want to make your water at least mildly acidic. The core of the problems with neutral to basic water is, I believe, iron. Without CO2 addition, you cannot reach acidic range with more than a fraction of one single German degree of KH.
Honestly, I'm about to make a tank with near-zero alkalinity but much increased content of magnesium and calcium (hardness). I have long-term difficulties with apparently easy plants - Echinodoruses, Cryptocorynes, and Bucephalandras. I want to explore this possibility, perhaps they (some of them) actually like such water. I'm planning to add bicarbonates to maintain pH between 6.6 and 7. Much less than 1 °dKH will be required for that.
John q
Member
Can't help with the cherry shrimp but Amano's and Tangerine tigers manage fine with 12ppm Calcium & 5ppm Magnesium approx 2.8 dgh. Amano's approx 2½ years old, Tangerines just over a year old.
MichaelJ
Member
There are certainly no reason to aim for 8 dGH with any dwarf shrimp I am aware of. The sweet spot for shrimps appears to be in the 4-6 dGH range. Yes, you can go quite a bit lower than 4 dGH if the food sources provides enough calcium and magnesium and if the pH is not exceeding low. It also vary slightly among species - the Tangerine @John q keeps are often quoted to be fine in the 3-5 dGH range. Regardless, I think it's a balancing act between food sources, Calcium/Magnesium in the water column (dGH) and pH. In my shrimp tank I keep dGH around 4.5 (it may be a lot closer to 4 due to uptake, but I target my WC water 4.5), pH 6.2 and fair amount of Calcium in the food sources - both snails and my diverse shrimps are thriving. In my other tank, where I don't keep shrimps but still have some snails, I'm around ~2.3 dGH and pH 6.2 - in that tank all my snails have clear signs of shell erosion (white brittle shells) and I feed them occasionally with Calcium rich algae wafers. Also, in both tanks I keep alkalinity at ~0.5 dKH in order to get a stable low pH (I don't inject CO2) - again only targeting the WC water so the actual dKH in the tanks is probably lower.
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Agree with the guys above, in my experience Tangerines seem to do fine in surprisingly low dGH/Calcium levels, but certainly for the cherry shrimp I've kept in the past (Bloody Mary's and Black Roses), production of new young drops off dramatically if parameters drop much below 4dGH, with 4-5dGH being the sweet spot for me. Conversely most Neocaridina will do fine in pretty high levels - I've kept them in 6dKH/12dGH tap water and they've bred fine, but Tangerines (indeed all Caridina I've kept), can't survive in those levels.
In an RO based system though the dGH can of course can be divorced from the dKH, and in all my tanks I run at zero dKH via remineralisation but with 4-5dGH for the shrimp for around 93ppm TDS.
In an RO based system though the dGH can of course can be divorced from the dKH, and in all my tanks I run at zero dKH via remineralisation but with 4-5dGH for the shrimp for around 93ppm TDS.
Thank you all for your replies. So it appears if I eventually do go down the 100% RODI route, as I am a Co2 user, the target would be around alkilinity of 2dKH and around 4-5 dGH for the livestock.
Also I have noticed that in historical UKAPS threads the thought used to be that one can grow all but a few species of plant without any problems in high KH water, even without iron chelates. I am sure there are some very talented aquascapers that have the ability to achieve this. All that I know, is locally to me if you are low tech, those that have success are mainly dosing iron (sometimes without even knowing it), and if co2 injected it needs to be chelated. Those that dont do this (including local fish shops I have spoken to), tend to end up with a algea bath and give up.
Interesting, when I first started to get iron issues, I used to think I was a rare case, but it appears from the threads on this forum to be more common than I thought.
Also I have noticed that in historical UKAPS threads the thought used to be that one can grow all but a few species of plant without any problems in high KH water, even without iron chelates. I am sure there are some very talented aquascapers that have the ability to achieve this. All that I know, is locally to me if you are low tech, those that have success are mainly dosing iron (sometimes without even knowing it), and if co2 injected it needs to be chelated. Those that dont do this (including local fish shops I have spoken to), tend to end up with a algea bath and give up.
Andy Pierce
Member
@Aquarium Gardens is proof you can have fantastic success with very high KH water (dKH 13+). It's definitely high tech... not sure what they do for iron.
0.5dKH is plenty - if you dose plenty of PO4 you might not even need that - I run zero dKH in all my RO tanks, even the CO2 injected ones.
