# [Wet Thumb Forum]-chelated iron



## perrush (Feb 24, 2003)

Hi,

not sure what you guys mean with 'chelated' iron ? How is this iron different from other Fe2+ or Fe3+ (from the chemical view)

I ask this because I was looking for a Fe fertiliser in bulk.

FeSO4.7H2O is available and gives me 20% Fe2+ The technical form costs less than €10/kg

But is this useable ??

and what about the Fe testkits ?? What do they measure ?? I read somewhere that 'chelated iron' levels and 'normal soluble iron' levels have different maximum values ????

anyone any guidance ??








Perrush


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## perrush (Feb 24, 2003)

Hi,

not sure what you guys mean with 'chelated' iron ? How is this iron different from other Fe2+ or Fe3+ (from the chemical view)

I ask this because I was looking for a Fe fertiliser in bulk.

FeSO4.7H2O is available and gives me 20% Fe2+ The technical form costs less than €10/kg

But is this useable ??

and what about the Fe testkits ?? What do they measure ?? I read somewhere that 'chelated iron' levels and 'normal soluble iron' levels have different maximum values ????

anyone any guidance ??








Perrush


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## Rex Grigg (Jan 22, 2004)

I will try and explain this. Chelated minerals are organically available to the plants. Inorganic iron is not available. Inorganic iron can become organic though the bacteria in the substrate.

As for the test kits don't waste your money.

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## Doomer (Feb 2, 2003)

Would it make sense to squirt Flourish Iron into the substrate rather than the water column ?


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## jpmtotoro (Feb 13, 2003)

flourish iron is chelated (or mostly) already if i remember correctly, thus making it available to the plants right off the bat.

JP


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## perrush (Feb 24, 2003)

> quote:
> 
> Originally posted by Rex Grigg:
> I will try and explain this. Chelated minerals are organically available to the plants. Inorganic iron is not available. Inorganic iron can become organic though the bacteria in the substrate.
> ...


Well that chelated is the one plants need, I know, but how does this chelated differ from 'inorganic' (as you name it)

As far as I understood Fe 2+ is what plants need, Fe 3+ they can't use. So that's why I asked if FeSO4.7H2O (ginving Fe 2+ in solution) would be a good iron source.

Or my question otherwise : How does a 'chelated' iron molecule look like ??

But I ask on some chemical message board.

For the testkits ....







don't you use a testkit to measure your Fe levels ??








Perrush


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## George Willms (Jul 28, 2004)

Actually, from what I remember Flourish Iron is a mix of both chealted and free iron. If you look on the web-site it says as much and that it includes 1% ferrous gluconate, which is not a chelated iron, but more like an iron sugar complex, which plants can use.

George


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## Rex Grigg (Jan 22, 2004)

Chelated iron is bonded to a chelating agent. Something like EDTA which if I can remember is a large organic molecule.

I do not use a Fe test kit as they are not at all accurate.

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## perrush (Feb 24, 2003)

> quote:
> 
> Originally posted by Rex Grigg:
> Chelated iron is bonded to a chelating agent. Something like EDTA which if I can remember is a large organic molecule.
> ...


Tnx Rex, a little more clear now.








Perrush


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## Jeremy S (Apr 9, 2006)

> quote:
> 
> Originally posted by Rex Grigg:
> As for the test kits don't waste your money.


Rex, if you don't use iron test kits then how do you know how much you need to add per week?


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## Roger Miller (Jun 19, 2004)

Just clarifying a few points:

Once iron is inside the plant it becomes hard to tell whether it is Fe+3 or Fe+2. The only reason that some sources say plants need Fe+2 is that the inorganic salts of Fe+2 are more soluble than the salts of Fe+3, so under natural conditions the Fe+2 is the only kind that plants can get in large enough amounts to serve their needs.

Chelated iron can be Fe+3 or Fe+2, depending on the type of chelate. EDTA and DTPA contain Fe+3 and iron gluconate contains Fe+2. I think that iron citrate may also contain Fe+2.

Iron gluconate *is* chelated iron. The complex isn't as strong as the FeEDTA complex or the FeDTPA complex.

If you could see an iron chelate it would look like a small to medium sized organic molecule wrapped up on itself. The middle of the molecule is the iron atom. The way the organic molecule wraps around the iron works to protect the iron from reactions. The name "chelate" is from the Greek (I think) word for "claw." That describes how the organic molecule wraps around the iron -- like the talons of a small hawk wrap around some hapless mouse.

I don't know what most iron chelates look like in bulk, but I do have a few pounds of Iron DTPA. It is an orangish-grey colored powder. Iron chelates are more commonly sold in solution.


Roger Miller


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## perrush (Feb 24, 2003)

@ Roger :

tnx Roger, you made it very clear what chelated iron is.

I guess you can't give me an idea why chelated iron is easier absorbed that 'normal' - soluble iron ? 
It doens't make sence because the total chelated molecule is much larger than a single Fe2+. But I searched google and it's clearly a common practice in plant fertilisation to fertilize with chelated metals. So I guess it is better, although I don't understand it at the moment.

But back to my question :

As I understand, plants have the ability to absorb other forms of iron than the chelated form, only it takes more time.

So dosing FeSO4 would help eventually, although it's not the best way.

What should I use as Fe-bulk-fertiliser instead ?
They sell chelated iron as a dietary supplement, but I guess this would be even more expensive as buying a commercial plantfertiliser. And it will surely not be 'pure'.

I saw you mentioned iron citrate. Is this also a chelated form ??
There is Iron (III) citrate tri hydrate (C6H5FeO7.3H2O), would this be the 'chelated' form I seek ? I don't think so, because this is just the iron salt of citric acid which will give me Fe(III) and the weak base of citric acid in solution. So the same effect as dosing FeSO4.

So I still don't know for sure why I shouldn't use FeSO4 and/or where I can find the Fe-EDTA in bulk.

- sorry for making it such a long post -

Perrush


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## Rex Grigg (Jan 22, 2004)

Jeremy,

I just watch my plants and dose a lot of iron. With a high light tank you need a lot of iron. The problem with test kits is that the iron gets bound up. You can dose and test and have say 0.2 ppm, test an hour later and you have none.

perrush,

Are there any Hydroponics stores in your area? They normally carry some type of iron chelate.
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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Originally posted by perrush:
> I guess you can't give me an idea why chelated iron is easier absorbed that 'normal' - soluble iron ?


Simply because without chelation iron isn't soluble. Under aquarium conditions Fe+3 forms highly insoluble hydroxides and oxyhydroxides that immediately come out of solution. Fe+2 oxidizes to Fe+3 and then precipitates. Small amounts of iron remain dissolved in soil water because soils usually provide chemical conditions that keep iron in the Fe+2 state and at concentrations adequate to supply plants.



> quote:
> 
> It doens't make sence because the total chelated molecule is much larger than a single Fe2+. But I searched google and it's clearly a common practice in plant fertilisation to fertilize with chelated metals. So I guess it is better, although I don't understand it at the moment.


Plants don't actually take in the chelated iron. Plants break the bond between the iron and a weak chelate like iron gluconate. Strong chelates like EDTA are more difficult. Most plant's can't break that bond. But light does break down the chelate, and as the chelate breaks down it produces a steady, very low concentration of Fe+2 that the plants can use.



> quote:
> 
> What should I use as Fe-bulk-fertiliser instead ?
> They sell chelated iron as a dietary supplement, but I guess this would be even more expensive as buying a commercial plantfertiliser. And it will surely not be 'pure'.


I can't suggest that you should use anything but chelated iron. I don't know about ferrous citrate, but I have used ferrous gluconate tablets sold as dietary suppliments. The dietary suppliments are *much* less expensive than commercial aquarium fertilizer.



> quote:
> 
> I saw you mentioned iron citrate. Is this also a chelated form ??
> There is Iron (III) citrate tri hydrate (C6H5FeO7.3H2O), would this be the 'chelated' form I seek ? I don't think so, because this is just the iron salt of citric acid which will give me Fe(III) and the weak base of citric acid in solution. So the same effect as dosing FeSO4.


At least one iron citrate is a chelate. I'm not sure whether that is the Iron (II) or Iron (III) compound, or whether both might be classified as chelates. The line between an iron chelate and a normal iron salt seems to be fairly fine. All of the iron cheiates I know of have the formula of an iron salt. Chelates are not distinguished by their formula, but by their structure. The organic ligand in a chelate deforms to place the iron molecule in 6-coordination, forming the "claw". That isn't typical behavior for a normal salt. While it isn't a distinguishing feature, it's important to note that the iron chelates we use remain associated in solution over a range of pH. Within that range the chelates don't dissociate when they dissolve, as many salts do. Outside their pH stability range the chelates do break down. I don't fully understand what happens when they break down.



> quote:
> 
> So I still don't know for sure why I shouldn't use FeSO4 and/or where I can find the Fe-EDTA in bulk.


I have used several pounds of FeSO4 in my yard trying to keep a maple tree from turning yellow in my alkaline soils. It is useful as a short-term soil acidifier, but pretty useless as an iron souce. That tree finally blew down in a storm and we had it removed, so I had most of a bag of FeSO4 left over to experiment with.

If you add FeSO4 to solution the ferrous iron will quickly oxidize to form ferric ion, which uses up oxygen in the water. Once it is oxidized it will precipitate to form ferric hydroxides. Then the plants can't get the iron.

If you try to mix a concentrated stock solution you will find that as the hydroxides precipitate the pH of the solution becomes very acidic. The oxygen content and pH eventually drop far enough that Fe+2 is stable in solution. At that point the mixture is usually an acidic, greyish-orange sludge that settles very slowly. If you add that solution to tank water the dissolved iron will (guess what) oxidize to ferric iron and quickly precipitate.

Here iron chelates are commonly available at nurseries in concentrated solutions or as dry bulk powders. That may not be true in Belgium because your soils are not alkaline like ours. Your farmers and gardeners would have little use for an iron chelate.

Roger Miller


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## perrush (Feb 24, 2003)

@ Roger :

waauuw ... you sure know your chemistry ;-)

Oke, now I know what to look for and why I must have those chelated metals. The next question : "Where to buy" is one I must solve myself, but I'll ask around here.



> quote:
> 
> The dietary suppliments are *much* less expensive than commercial aquarium fertilizer


This was a surprise to me, but if you say so.

Perrush


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## imported_Svennovitch (Feb 1, 2003)

perrush,

if you find a cheap source, please let me know!
I am always interested in alternatives for the trace mix i am using now.

Cheers,
Sven

btw. nice meeting you, didn't know there were other Belgians on the boards


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## perrush (Feb 24, 2003)

> quote:
> 
> btw. nice meeting you, didn't know there were other Belgians on the boards


hehe, probably just the two of us. Never mind that, "united we stand strong" , or how do they say that here ?? ;-)

Perrush


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## imported_Svennovitch (Feb 1, 2003)

Especially on a day like this








Have a great national holiday !

Any chance for trading some plants, fish, aquarium material,...
Where do you live in Belgium? Dutch, French?

Groeten,
Sven


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Originally posted by perrush:
> 
> ...


Actually I rechecked and need to correct myself. I was confused about the concentration of iron in the iron suppliments. I made a quick comparison at the grocery store and found that for the same amount of iron, the dietary suppliments were a bit *more* expensive than the aquarium product.

Roger Miller


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## perrush (Feb 24, 2003)

> quote:
> 
> and found that for the same amount of iron, the dietary suppliments were a bit *more* expensive than the aquarium product.


hehe, never mind

but spoken of *a bit more expensive*

a bottle of Iron Flourish 250 ml costs overhere €8 ... in the AB store 500 ml for $10.5








That's almost twice as much








¨
Probably the same for flourite ... €24 for a 7 kg bag ...


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## Anthon (Feb 26, 2004)

Hi perrush

Have you ever heard about "algoflash soins antichlorose" as a cheap chelated iron supplier ?

Many french aquarist use it. I don't know if you can find this product in belgium but here you can buy 500 mL for around 7 euros. It brings 2% of EDTA chelated iron.

I don't like very much this product because it simply brings iron and not other micro-nutrients. But it's a cheap iron source.



Svennovitch i may be OK to exchange plants with you.

_____________________________
Sorry for my bad english ...


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## imported_Svennovitch (Feb 1, 2003)

Salut Anthony,

comment ça va?
Où est-ce que tu habites en France? Pas trop loin, j'espère? Avec le temps qu'on a pour le moment, je ne pense pas que les plantes survivraient trois jours emballées? Peut-être dans quelques mois? Quelles plantes est-ce que t'en as besoin? Et quelles plantes est-ce que tu peut échanger?

Je connais pas l'algoflash, mais je n'aime pas les produits qui contient uniquement le fer moi-même. 

Je suis heureux de t'avoir rencontré!
Sven

Excuse-moi pour mon Français terrible...


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## perrush (Feb 24, 2003)

> quote:
> 
> Originally posted by Svennovitch:
> Excuse-moi pour mon Français terrible...


@ Svennovitch :
wise guy









@ Anthony :
€7 for 500 ml doens't sound a lot but you have to take into the concentration account.

2% of iron ??
flourish Iron states : "Guaranteed Analysis: Fe (Iron/Ferrous gluconate): 1.00%"

both seems not that much to me









And I only want a Fe fertiliser, so that's not the problem

Perrush


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## imported_Svennovitch (Feb 1, 2003)

lol @ perrush

Well, it took me about 30 minutes to make that reply.
So...

But i was only commenting his "sorry for my bad english", while I don't see what is wrong with it. Irony, you know









Sven


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## Anthon (Feb 26, 2004)

Svennovitch 
I private message you for a possible exchange.
I put this signature because I know I'm able to make so enormous grammar mistakes. It also took me a long time to write in english.

Perrush
€7 for 500 mL 2% iron EDTA vs €8 for 250 ml 1% iron gluconate means algoflash iron is around 4 times less expensive than flourish.
If you can't find this garden fertilizer on local garden store I know it is also available online but I can't remind the URL.
I don't think you can found liquid chelated iron source with a very higher concentration than 2% (solubility problems ???)

_____________________________
Sorry for my bad english ...


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## perrush (Feb 24, 2003)

> quote:
> 
> Originally posted by Anthony:I don't think you can found liquid chelated iron source with a very higher concentration than 2% (solubility problems ???)


this was my point ... both are fairly low in Iron content.

Perrush


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## Jack11 (Mar 30, 2004)

Roger,
In the dietary supplements you described above:


> quote:
> 
> I have used ferrous gluconate tablets sold as dietary suppliments


Did these tablets contain other ingredients. All the iron gluconate tablets I've seen contain a number of other ingredients. For example:Chlelated Iron Complex. Do you see anything to avoid in such a tablet? Is it worth as a fertilizer supplement? Thanks.
Jack

Ah Hah! You're supposed to put the plants IN the water...


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## imported_Svennovitch (Feb 1, 2003)

Anthony,

you English is fine. I am sure we all understand you









PM me anytime you want to!

Ciao,
Sven


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## Anthon (Feb 26, 2004)

Sven I opened a private topic for you (I don't know how to send PM from this board)

_____________________________
Sorry for my bad english ...


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## imported_Svennovitch (Feb 1, 2003)

Anthony,

j'ai repondu


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## perrush (Feb 24, 2003)

@ Anthony :

I guess you means this produkt :
http://www.jardin.ch/Algoflash/reverdissant.html

problem that I can't find any supplier in Belgium or Holland. Also found no on-line shop in France (because my French is very bad and I can hardly read anything  )

do you have any suggentions ? links ?

@ All :

on : http://www.litemanu.com/cgi-bin/htmlos.cgi/00159.1.46592105363
they sell Iron Chelate for $19 a lb. Is this pure ?? how many % is it ?? anyone bougth it ??

Perrush


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## Anthon (Feb 26, 2004)

perrush you can buy algoflash online here :
http://www.plantes-et-jardins.com/catalogue/catalogue4.asp?id_references=12098&id_variations=7403

They can sell to Belgium but if you only buy 1 bottle it is quite expensive with transport (€6,30 for fertilizer + €8,90 for port).

For your second link if I were you I will send an email to obtain technical data of this chelated iron (what is the chelator, what is the purity, ...)

_____________________________
Sorry for my bad english ...


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## Mortadelo (Mar 14, 2004)

Anthony, do you mean many french aquarists succesfully use FeEDTA with no other micronutrient source?. No chlorosis?, no mineral deficiency?.

A few folks here use FeEDDHA without problems. This makes me think iron is the only micronutrient really needed in planted aquariums (ussuming the other minerals come from fish food and water changes).

Please, forgive my poor english, it is 02:40 AM here, I just came home and had too much beer and Kalimoxo (red wine + coke + ice) yum, yum!!.

Saludos mon ami.

My planted aquarium blog
http://www22.brinkster.com/aguaverde/articulos/diario.htm


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## Anthon (Feb 26, 2004)

Mortaledo :
I think the only aquarists who succeed using only Fe-EDTA are those with high fish load.
I talked about this product because perrush is looking for a cheap source of iron.

wine + coke ? What a strange mix ... never heard about this in France.

Hasta luego amigo

_____________________________
Sorry for my bad english ...


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## imported_Svennovitch (Feb 1, 2003)

OMG, talk about addiction!!
You come home from a bar, had a few drinks, but still checking AB









I don't think they like hearing that in France, mixing wine with coke









Sven


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## Jack11 (Mar 30, 2004)

Bump.


> quote:
> 
> Chelated Iron Complex. Do you see anything to avoid in such a tablet? Is it worth as a fertilizer supplement? Thanks.


Anybody??
Jack

Ah Hah! You're supposed to put the plants IN the water...


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## Roger Miller (Jun 19, 2004)

There's a lot of vitamins and minerals in the tablet that you don't necessarily need in your aquarium. There also isn't as much iron as you might get for the same price or less from an iron-only suppliment.

For comparison, that tablet contains 90 mg of iron gluconate, which would yield about 10 mg of iron. For about the same price per tablet you can probably go down to the grocery store and pick up iron gluconate suppliments that don't provide other nutrients, but give several times as much iron.

The tablets I have contain 325 mg of iron gluconate and that yields 37 mg of iron. One tablet doses a 100 gallon tank to about 0.1 mg/l of iron.


Roger Miller


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## Jack11 (Mar 30, 2004)

Roger,
What is the brand name for the supplement you've described. Obviously, this is more what I'm looking for. Thanks for the reply, I didn't want to buy this with out getting any input.
Jack

Hmm...Something clever, funny, and contemplative...
Ahh, @*#%!...Yeah, that's it!


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## Roger Miller (Jun 19, 2004)

Mine are "Nature's Bounty" brand. There are any number of other brands that pretty much alike. When I checked prices on iron gluconate tablets (earlier in this thread) the local grocery had two brnnds that were comparable with the ones I have.


Roger Miller


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## Jack11 (Mar 30, 2004)

At my local grocery store, I was able to find two kinds of "pure" iron supplements. One, was composed of FeSO4, and the other, iron gluconate. The iron sulphate contained higher levels, in mgs, of iron than the iron gluconate. However, I don't know whether this would be in a form suitable for fertilization use. Further, I am trying to calculate what amount of either of these products would be dosed. Is the important number the elemental iron in mgs? Or, is it the larger, iron number which, I assume, is the total amount of iron in each tablet? Thanks
Jack

Hmm...Something clever, funny, and contemplative...
Ahh, @*#%!...Yeah, that's it!


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Originally posted by Jack11:
> The iron sulphate contained higher levels, in mgs, of iron than the iron gluconate. However, I don't know whether this would be in a form suitable for fertilization use.


Jack,

That's the question that started this thread. You should get a pretty good discussion just by rereading the first few posts. Short form -- chelated is better.



> quote:
> 
> Further, I am trying to calculate what amount of either of these products would be dosed. Is the important number the elemental iron in mgs? Or, is it the larger, iron number which, I assume, is the total amount of iron in each tablet?


You start with the iron in milligrams. The larger number should be the amount of iron gluconate or iron sulfate, which includes the iron plus the weight of however much gluconate or sulfate is present.

When I was using iron gluconate tablets regularly I was using them in the substrate. I would halve or quarter the tablets and push them into the substrate below a plant I thought needed a good dose. I've never tried dissolving them.

Roger Miller


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## perrush (Feb 24, 2003)

@ Roger :

I've been reading a lot about fertilizers lately and came across several posts of you at different places








Even seen some discussions with seachems employees LOL









now you surely know your business. What should I understand under : *hydrogeologist* ???









now back to topic.

In the agroculture they use strong chelating agents like EDTA, DTPA, HEDTA and so on
Seachem uses a weak (partial) chelator : gluconate.

(see for instance : http://www.satyajitchemicals.com/micronut.htm)

Still don't know if gluconate will be better the EDTA. But if agroculture uses EDTA (which is more expensive !) I tend to think this is better. (you already said that in a 1997 respons I read somewhere)

I my search to bulk chemicals I was able to locate Fe-EDTA (as well as *ALL* other micronutrients in EDTA form), Fe-DTPA, Fe-HEDTA at prices you won't believe (lets say less than 1/5 of seachems Iron (recalculated to the same concentration))

now my question(s). 
- Why I'm I the first who was able to locate such (are wasn't I







)

- Would it be usefull to go on with this and try to distribute this (and a traces mix) in a legal way - would there be a market for this ?
Keep in mind that I could make a *trace mix at wish.

Only problem ... I must take it in bulk, meaning 25 kg or more







.

So I would like to hear any comments, thougths on this subject.

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush

[This message was edited by perrush on Sat August 02 2003 at 05:01 AM.]*


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## Rex Grigg (Jan 22, 2004)

I have been using a iron chelate ETDA for a couple of months now. The same store also sells other chelated minerals. I pay $19 USD for 1 lb of the iron chelate. This makes it MUCH cheaper than the Seachem product.

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## perrush (Feb 24, 2003)

@ Rex :

That must be from www.litemanu.com , I asked about that produkt in this thread, got no respons.
I also mailed them for the specs, no respons so far.

What does the etiket say ? I assume it's EDTA ferric sodium salt (1 Fe and 1 Na). Does it stated a moleculair weigth ? A formula ? How much do you use ? ect ...

and believe me, $20 for a pound is still alot of money, but it's a start









--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## Roger Miller (Jun 19, 2004)

Perrush,

Be careful about using my old letters. I may know more now than I used to









I don't consider EDTA to be better than gluconate. But without a question EDTA and gluconate are chemically very different and they need to be used differently.

Most of the material you read about fertilizing with iron is based on experience with EDTA. I don't know of anyone -- including Seachem themselves -- who has tried to set up a fertilizing schedule or method that is tailored to the chemical behavior of iron gluconate.

If you want to use the widespread recommendations about how and how much iron you need to fertilize with then you should probably use iron-EDTA. If you're willing to experiment a little with different methods then you should be able to get equal results from iron gluconate.

Roger Miller


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## George Willms (Jul 28, 2004)

I've been using iron gluconate for a while now. At first I think I was using too much (I was dosing daily with a 2% solution), growth in my plants actually slowed down. I've since cut back to dosing every 2nd or 3rd day and have had much better growth in my plants. Specifically my Red Temple has exploded. I'm hoping my other red plants aren't too far behind, as they seem to be the ones that weren't growing at all.

George

Tank specs in profile


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## perrush (Feb 24, 2003)

@ George :

Do you use flourish ? Or did you obtain it elsewhere ? Cost ?

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## Anthon (Feb 26, 2004)

If they use strong chelator in agroculture I think it's a question of stability along the time. It's easy to add fertiliser to a tank every day, it's harder to add fertiliser on a field every day...

_____________________________
Sorry for my bad english ...


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## perrush (Feb 24, 2003)

@ Anthony :

If its only a question of 'strong' than EDTA is the better choise (who really wants to fertilize daily ??) 

The only negative I've read about EDTA (think it came from seachem, but not sure) is that EDTA is able to extract metals from plants !!! I sounds crazy, because the agro industry uses it for decades, I guess they did some research too.

Gluconate is uses for humans (and animals ?). But I think the biochemical processes for animals are slightly different from those of plants.

@ All :

still no respons if there is a need for a cheap trace mix, specially designed for plants in aquaria. So I guess the need isn't that great.

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## Rex Grigg (Jan 22, 2004)

All I know is it is iron chelate. With ETDA. I mixed 2 tablespoons in 500 ml of water and dose around 5 mls of this twice a week. $20 a pound might sound high but it's pretty much a life time supply of iron.

As for a trace mineral mix designed for aquatic use. I can have one made. There's just one small problem. The minimum order is 900 lbs.

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## George Willms (Jul 28, 2004)

Perrush, I use my own solution of ferrous gluconate. I can't tell you the cost as I got it from work. One of the benefits to working with chemicals: companies send us free samples.









George

Tank specs in profile


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## imported_Davo (Apr 12, 2003)

Rex,

Do you dose both trace elements and chelated iron seperately. Doesn't the trace element mix already have iron in it?

I have some chelated iron and the container it came in states that it is 13%W/W EDTA. Is this percentage too high??

Thanks,
Dave.


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## Rex Grigg (Jan 22, 2004)

I do dose both traces and iron. The trace mix has iron but to get and keep the necessary levels of iron I would have copper levels that I'm not comfortable with. So I use the iron chelate. The chelated iron you have sounds about right. I think mine is 14%.

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## perrush (Feb 24, 2003)

this thing is running out of all proportions 

found this :
http://users.pandora.be/perrush/chelatoren.jpg

so Fe-EDTA isn't stable above pH=6.5

Also they aren't stable in light !!!

Would be interesting to see how gluconate compares to this.

I think I have to pay a visit to the universities library









--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## Roger Miller (Jun 19, 2004)

Perrush,

The iron in ferric-EDTA isn't directly available to plants. The complex has to break down before the iron becomes useful.

I don't know what implication there is to the pH stability range. EDTA is used in chelation therapy for metal poisoning when it must form chelates at pH well above its supposed pH range.

The photosensitivity of ferric-EDTA is interesting. When the complex catches a photon of the correct frequency it becomes activated. In order to fall back to a more stable state the iron grabs an electron from the EDTA and is reduced to ferrous ion; the EDTA is oxidized and breaks down. The ferrous ion is available to plants, but it also quickly forms other complexes and/or is oxidized back to ferric ion. The EDTA may break down to a number of compounds, some of which are chelating ligands themselves.

Other Ferric iron chelates are subject to the same process -- called "photoreduction." Ferrous iron chelates (like gluconate) are not subject to photoreduction.


Roger Miller


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## perrush (Feb 24, 2003)

> quote:
> 
> Originally posted by Roger Miller:
> 
> ...


If the EDTA breaksdown too fast and all at once, it is of no use. If it stays long enough in solution, and eventually degrades, it's no problem.
So the question is HOW stable is it above that range.



> quote:
> 
> Originally posted by Roger Miller:
> 
> Other Ferric iron chelates are subject to the same process -- called "photoreduction." Ferrous iron chelates (like gluconate) are not subject to photoreduction.


Again the same question to be solved : How fast goes this fotoreduction in our aqua's, how stable is gluconate in the aquaria (towards the pH range AND toward the bacteria)

So both EDTA and gluconate or used in aquaria, but obvious one or the other will be more efficient (or will EDDH(M)A be the best choice ?)

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## Jack11 (Mar 30, 2004)

As interested in the answer to perrush's question as I am, some of this chemistry has gone over my head. If I am looking for an iron to supplement my fertilizer regime for a planted tank is it better to use a product that has ferrous gluconate (supplement pills) or, an EDTA chelate of ferrous sulfate? I think the answer based on the posts above is the gluconate tablets but, I would like to clarify this before buying anything. The local nursery has a liquid trace mix with 
Fe (chelated) at 3.25%
Mn (chelated) 0.15%
Zn (chelated) 0.16%
Cu (chelated) 0.05%
I don't know if this is useful for the iron/copper ratio anyway but, I was considering it. At the bottom it states that each ingredient is EDTA chelated ferrous sulfate, or EDTA copper sulfate. Thanks and I'll try to re-read and decipher the chem.
Jack

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## perrush (Feb 24, 2003)

Hi Jack,

First, those ratios in the mix are fine, although a little low in comparison.

As for the gluconate - EDTA - EDDH(M)A - choise. There are 3 stabilities to consider :
1) pH stability
2) light stability
3) bacterial stability

I have no complete data on which chelate is the most stable for those 3 points.

Gluconate isn't effected by light (says Roger), all other are (but at which content ?? I read somewhere that the half-time in light was something of days, if so, than this is not that important if we dose regulary.

gluconate will be less stable to bacteria I guess, because it's much more 'natural'. But again, no exact data.

glocunate isn't a full chelator, so some Fe won't be chelated, EDTA and the other are.

So lots of questions still to be solved. But Fe-EDTA is often used, so it will do it's thing I guess.

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## Roger Miller (Jun 19, 2004)

Iron gluconate and iron-EDTA both work. You can use either one.

Perrush, the half life for iron EDTA is variable. The spectrum and intensity of the light are both factors. I've read one report that one day of exposure to full sun will eliminate EDTA commonly found in municipal sewage. In simulation I ran for aquarium conditions I found that when dosing a tank up to 0.1 mg/l the half life needed to be on theo order of a few days or the plants would become iron deficient. With a longer half life the EDTA does not supply biologically available iron at a rate fast enough to stay ahead of the precipitation of iron into biologically unavailable forms.


Roger Miller


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