# Clay balls



## Soilwork (10 Feb 2017)

If I was to add a small pea size ball of red clay under a plant, would it be able to obtain iron from it?


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## zozo (10 Feb 2017)

Yes.. 
https://www.ukaps.org/index.php?page=guide-to-substrates
scroll down to* "*API First Layer Pure Laterite"


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## dw1305 (10 Feb 2017)

Hi all, 





Soilwork said:


> If I was to add a small pea size ball of red clay under a plant, would it be able to obtain iron from it?


It depends upon the level of oxygenation of the substrate, if the substrate is all aerobic, then the iron (Fe) will remain as iron III (hydr)oxides, and never become available. 

If the substrate contains anaerobic areas the reservoir of iron in the clay balls (you know they contain iron, they are red) will become plant  available.  

Because clays have small particle size, it is likely that some iron ions will become available in most substrates. 

If your tank has very hard water the problem is that the iron ions will rapidly form other insoluble compounds, if you have soft water and low pH, they will remain plant available.

You can tell the iron content of the clay iron III oxide (<"rust">) in the clay by the colour. It is the same reason bricks are red, all the iron is oxidised and unavailable. If you take a green ferrous (Fe II) <"gley soil"> and bake it, it will change colour from green to red (ferric - Fe III). 

<"Lateritic soils"> form in tropical areas, under conditions of high rainfall, because all the soluble cations are leached, leaving only the insoluble aluminum (Al) and iron oxides behind. They will remain in this state almost eternally if conditions remain aerobic. 

cheers Darrel


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## Soilwork (10 Feb 2017)

Thanks both.  Great explanation. 

So you would expect the average aquarium substrate to have anaerobic areas that can facilitate the availability of plant friendly iron?


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## alto (10 Feb 2017)

IIRC the APD covered Clay Balls _ad nauseum_ .... I mean really how much can one say about Clay Balls - well ALOT as it turns out
The Krib likely has some summarized discussions (sorry not willing to bore myself again digging them out )

Oh yeah - more relevant to your other Soil thread, but again bore (as in tunnel  ) your way through APD archives & The Krib for ALOT of soil talk


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## dw1305 (10 Feb 2017)

Hi all,





Soilwork said:


> So you would expect the average aquarium substrate to have anaerobic areas that can facilitate the availability of plant friendly iron?


Yes, it should do. It might take a while until the substrate "matures".

Plants that naturally grow in aquatic situations will normally grow in reduced sediments, and a plant that is seasonally inundated conditions may grow in sediments that are alternately oxidising and reducing.

Plants with a reasonably robust root system, like most _Echinodorus, _or one of the larger _Cryptocoryne spp. _should help produce a rhizosphere where iron reduction can occur. We know that Fe(III)-reducing bacteria (FeRB) are important in this process, and leaky roots produce a rhizosphere (one with fluctuating REDOX values) that produces suitable conditions for them.

I'm not aware of any work specifically on iron reducing and oxidising bacteria in aquarium substrates, but <"they are pretty universal in nature"> so I would be very surprised if this isn't also true of undisturbed aquarium substrates as well.

cheers Darrel


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## dw1305 (10 Feb 2017)

Hi all,





alto said:


> The Krib likely has some summarized discussions (sorry not willing to bore myself again digging them out )


It does. <"Everything you want to know about laterite">.

cheers Darrel


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## Soilwork (10 Feb 2017)

Easylife ferro uses Fe II.  Does it have an affinity to become fe III in an oxygenated water colum or does the DPTA keep it in solution longer as Fe II.  Does light still play a role in the 'bond breaking' between iron and the chelate DPTA assuming Ferro does use DPTA and not EDTA.


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## xim (10 Feb 2017)

Soilwork said:


> Easylife ferro uses Fe II.  Does it have an affinity to become fe III in an oxygenated water colum or does the DPTA keep it in solution longer as Fe II.  Does light still play a role in the 'bond breaking' between iron and the chelate DPTA assuming Ferro does use DPTA and not EDTA.



Fe chelated with EDTA (and DTPA—I would add) is FEIII only. But it is still available to plants because it is chelated.

There is a post from Greg Morin, the president and CEO of Seachem, if you're interested.
http://www.thekrib.com/Plants/Fertilizer/gluconate.html#5


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## Soilwork (11 Feb 2017)

Great post thanks.  So it looks like easylife use gluconate as it says the source is fe II on the back of the bottle. I did see the precipitation too but I made the mistake of adding kh2po4 from macros at the same time.  Still plants responded well.


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## Soilwork (7 Nov 2017)

Just resurrecting this as it was my thread.  Does it matter if the red clay has dried?


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## dw1305 (7 Nov 2017)

Hi all,





Soilwork said:


> Just resurrecting this as it was my thread.  Does it matter if the red clay has dried?


No, the clay is red because the iron is oxidised (ferric oxide - Fe2O3) already.  If you soak it won't change colour. If you soaked the clay without oxygen for long enough the iron would be reduced and the red colour would be replaced by the <"grey-green of ferrous (Fe++) oxides">. If the substrate becomes anaerobic that iron becomes potentially available, if it remains aerobic then it remains as ferric oxide <"potentially eternally">.

cheers Darrel


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