# [Wet Thumb Forum]-Iron dosing and hard water



## Bert H (Mar 2, 2004)

I have hard water, kh ~9.5. I have noticed that if I add iron at the recommended doseage (Flourish iron) about 30-45 minutes after adding I get a slight haziness in the tank. I remember reading a while back somewhere that this is some form of precipitate with the iron and the hard water (Iron carbonate perhaps?). 
My question is, has anyone else encountered this before? If so, how do you deal with it?
I have resorted to adding 0.25ml of iron on a daily basis to my 29 gal, since with this amount I don't notice (doesn't mean it isn't there) any precipitation forming.
Does anyone know if once the precipitate forms then does the iron become unuseable to the plants?
I will also e-mail the folks at Seachem to see what they say.
Thanks for any info.

Bert.


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## Bert H (Mar 2, 2004)

I have hard water, kh ~9.5. I have noticed that if I add iron at the recommended doseage (Flourish iron) about 30-45 minutes after adding I get a slight haziness in the tank. I remember reading a while back somewhere that this is some form of precipitate with the iron and the hard water (Iron carbonate perhaps?). 
My question is, has anyone else encountered this before? If so, how do you deal with it?
I have resorted to adding 0.25ml of iron on a daily basis to my 29 gal, since with this amount I don't notice (doesn't mean it isn't there) any precipitation forming.
Does anyone know if once the precipitate forms then does the iron become unuseable to the plants?
I will also e-mail the folks at Seachem to see what they say.
Thanks for any info.

Bert.


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## Roger Miller (Jun 19, 2004)

Let us know what Seachem says. I would be a little surprised if the iron in a normal dose of Seachem Iron could cause cloudiness in a hard-water tank.

The daily dosing that you're using is probably the best way to dose Seachem Iron.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## Wheeler (Feb 8, 2004)

That's odd. I add 3ml's of Flourish iron per day, plus 3ml's of another trace mix, to a 20 gallon tank and I don't see anything like that. My kh is ~7, though.

BTW, a KH of 9.5 isn't especially hard. Nothing to be suspicious of anyhow. Isn't Florida all limestone? I'm surpised that your water isn't harder than that...

Best wishes,
John Wheeler


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## tsunami06 (Feb 6, 2003)

I think they use a water softener at the plants in Miami, Wheeler. My tap water has always registered with a KH of 4 and a GH of 5. Just perfect for plants.









Carlos

-------------------------
"If you hear a voice within you say 'you cannot paint,' then by all means paint, and that voice will be silenced." -- Van Gogh


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## Bert H (Mar 2, 2004)

The folks at Seachem answered my questions. They say you will get ferrous carbonate to precipitate out when the kh is above 6. According to Seachem, once it precipitates, it no longer is available for uptake via the foliage portioins, which is what the product is intended for, but would be available for uptake through the roots. 

I have to give kudos to Seachem. Anytime I have e-mailed them with a technical question about any of their products, I have received a reply within 1 day of my question. That's the kind of customer service that's becoming rare nowadays.

John and Carlos, as far my water hardness, we have a well providing our home water (northwestern portion of Alachua county). The well's at 150 feet, real good water, knock on wood. Peninsular Florida's water comes from underground aquifers full of limestone, but city water is treated therefore knocking down the hardness. 

Bert.


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## Freemann (Mar 19, 2004)

The folks at Seachem answered my questions.


> quote:
> 
> They say you will get ferrous carbonate to precipitate out when the kh is above 6. According to Seachem, once it precipitates, it no longer is available for uptake via the foliage portioins, which is what the product is intended for, but would be available for uptake through the roots


So let me get this strait is seachem telling us that in anything above Kh 6 iron glouconate turns to ferrous carbonate (and how fast this is happening)? If that is the case they should write it in the label, prolly half of us are having Kh higher than 6, is that true for iron glouconate can somebody verify this?


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## Planted Engineer (Jan 15, 2004)

Hi,

Has anyone verified this with Seachem - I can see from the number of views that this wasn't percepted as an alarm signal. Is it because no body uses Seachem? no body has a KH>6?









PE.


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## Rex Grigg (Jan 22, 2004)

Well I have a kH under 6. In fact my tap water kH is under 1. I normally try and get my tanks up around kH 3. Lots of people in the Pacific NW have very soft water.










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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Originally posted by Planted Engineer:
> Has anyone verified this with Seachem - I can see from the number of views that this wasn't percepted as an alarm signal. Is it because no body uses Seachem? no body has a KH>6?


The information was reported from Seachem so there doesn't seem like a lot of reason to verify it again. I suspect people aren't more worried about it because Bert H's observation of cloudiness after dosing isn't very common and because the product seems to work anyway.

I still find the ferrous carbonate reaction a little surprising. I have the software to check on that but I'm missing information or even a reasonable estimate on the stability constant for ferrous gluconate.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## Bert H (Mar 2, 2004)

Roger,

I'd be curious if you did any measurements what you came up with. As I mentioned in my original post, I am now dosing 0.25ml daily on my 29gal. I figure as long as I keep it below the Ksp of ferrous carbonate I should be OK. And I must say, since I started dosing this way, my A. reinicki is redder; and my lobelia, and bacopa seem to be bushier and growing faster.

Bert.


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## Wheeler (Feb 8, 2004)

I'm not super convinced of the efficacy of foliar uptake anyway. Plants seem to prefer taking it through the roots. Why else would we have to dump so much in for so little to be utilized. Most ends up in the substrate anyhow...

It was my understanding that there is generally no available iron in natural bodies of exposed water anyway... It has all been captured by the substrate. Is this right?

Best wishes,
John Wheeler


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Originally posted by Wheeler:
> It was my understanding that there is generally no available iron in natural bodies of exposed water anyway... It has all been captured by the substrate. Is this right?


Apparently not, or at least not always. I did a search for data from rivers in the US and came up with a useful dataset for streams in the Apalachicola-Chatahoochie-Flint basin (say that 5 times fast) that drains areas in Georgia, Alabama and Florida.

Most of the 100s of samples in the database contained a few tenths of a ppm of dissolved iron. My initial assumption was that the iron would be present in organic complexes. In that case I thought the iron should correlate with dissolved organic carbon. A quick perusal of the data suggests no such correlation.

So in at least one river basin the water commonly contains dissolved iron. It's hard for me to say how much of that is plant-available,

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## Roger Miller (Jun 19, 2004)

Bert,

My water has about 7 dKH (variable) and I use Seachem Iron. I've been dosing my 150 gallon tank with 0.5 ml/day since last summer and about 1 ml/day recently. Most of the plants are fine. Where there are problems I don't think the problems are due to iron deficiency.

Redder alternanthera and bushier lobelia and bacopa aren't reactions I would expect to find associated with a change in iron dosing. Iron shortage appears as interveinal chlorosis in new growth. Increasing the iron levels can cure those symptoms and may cause a general greening of plants that don't show interveinal chlorosis.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## MarcinB (Apr 16, 2004)

> quote:
> 
> Originally posted by Roger Miller:
> So in at least one river basin the water commonly contains dissolved iron.


I did a quick search for iron concentrations in Polish lakes. The values are in the range of 0,1 to 0,9ppm.

150L (40G) planted tank
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## Roger Miller (Jun 19, 2004)

I just did a quick and dirty calculation of what it would take to get ferrous carbonate to precipitate after adding Flourish Iron. If I did the calculations right (always a serious question) then it would be possible. The catch is that at low or moderate buffer capacities the pH required to make ferrous carbonate precipitate is higher than normal for a planted tank. If the water is very well buffered then a normal dose of Seachem Iron could cause ferrous carbonate to precipitate at a realistic pH.

After wrangling the formulas a little I came up with a relationship between KH and pH that gives the maximum dose (in ml per 200 liters) of Flourish Iron that you can use before you get the precipitate.

The formula is:

n=(10^(8.94-pH))/KH

The recommended dose  is 5 ml/200 liters. The table below shows the maximum dose you can use under different conditions typical for planted tanks:

pH ... KH degrees ..... n ml/200 liters
6.5 ......... 2 ..................... 141
6.8 ......... 4 ....................... 31
7.0 ......... 6 ....................... 13
7.2 ......... 9 ......................... 6
7.6 ....... 24 ......................... 0.8

This is just a sample of conditions selected so that CO2 is about 20 ppm. Obviously if the KH in your water is low then you don't have to worry about losing your Flourish Iron as ferrous carbonate. In fact, the recommended dose (5) looks good up to KH 9, pH 7.2. If the KH in your water is high then you need to use smaller, more frequent doses to avoid having ferrous carbonate precipitating.

I don't need to worry about Flourish Iron precipitating but I think with Flourish Iron that small daily doses work best anyway.

I should point out that I have not discussed this with anyone at Seachem, they have done nothing that signals any kind of agreement with these results and they may even be upset by the whole thing. In fact, I can't even represent the results as being necessarily right or useful for any purpose. So there.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## Planted Engineer (Jan 15, 2004)

Roger,

Back engineering your formula like a good planted engineer...









Let's take the PH=7 and KH=6 combo. 13 mL / 200L is 65 mL per 1000L = 0.65 ppm.

Now inside that bottle... - they have 10000 ppm of the ferrous gluconate. So it means times 15,000 - so it must have a PH number below 3 (I don't have a calculator here but at least 4 digits below) - Am I correct?

So if I prepare a solution and pour 1% ferrous gluconate into a bottle filled with tap water then all I get is ferrous carbonate - yez?

So they put lot's of orange guice inside that bottle. Do fish like orange juice?









PE.


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## Roger Miller (Jun 19, 2004)

There's probably no KH (at least from carbonate and bicarbonate) inside the bottle. Iron carbonate would not precipitate no matter what the pH.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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