Hobby laterite balls? Any reviews?

[tiger15]

Hi @dw1305

On page 132 (Third Edition), Ecology of the Planted Aquarium, Diana Walstad has a section on the topic of Metal Toxicity. She mixed potting soil with laterite and the result was high iron levels in the water. Floating plants were the first to suffer, followed by Java Fern and then, rooted plants detached from the substrate and floated to the surface.

Thus, under some conditions, laterite is more soluble than perhaps we would expect.

JPC

With mixture of potting soil and laterite, it is unknowable where the soluble iron came from. Potting soil tends to be acidic and reducing due to presence of organic and micros that favors solubility of iron, besides the soil itself contains iron. Unless the test is conducted on laterite alone as control, the conclusion is premature.

Laterite, fluorite, and hydroton are all baked clay pellets that contain iron and other minerals. While the list of minerals is impressive per vendors information, they are chemically bound and largely biologically unavailable. For example, oxygen is plentiful as oxide, but it is not breathable.

 

[jaypeecee]

With mixture of potting soil and laterite, it is unknowable where the soluble iron came from. Potting soil tends to be acidic and reducing due to presence of organic and micros that favors solubility of iron, besides the soil itself contains iron. Unless the test is conducted on laterite alone as control, the conclusion is premature.

Hi @tiger15

Fair comment. Perhaps I should have quoted more of what Diana Walstad says in her book. Here goes:

"I believe that the strong acidity and high humus content of the potting soil solubilized massive amounts of iron from the laterite causing iron toxicity to plants".

It's a long time since I used laterite and I don't have any available. But, it would be a very simple experiment to set up in order to investigate this further for anyone who wished to do so.

JPC

 

[Sarpijk]

After about two years my crypts seemed a bit off. I have seen that after some time the Hobby Laterite balls turn to dust so I figured they should be replaced. I got another box, it is totally anecdotal but in my experience they help with extra nutrients.

 

[jaypeecee]

You can legitimately call "Flourite" "iron rich", but so is a <"red house brick"> and the iron is equally soluble in either case.

Hi @dw1305

I fail to understand how iron in a red house brick could be considered water-soluble. If this was the case, wouldn't our houses be slowly eroded whenever we get a downpour of rain? I have never used Seachem Flourite but I did use laterite many years ago. And, as I mentioned immediately above, Diana Walstad demonstrated that laterite releases iron into the aquarium water.

Something doesn't tally or am I overlooking something? No doubt you will have already seen the following but I certainly found it well worth another read:

Everything You Want to Know About Laterite!

JPC

 

[Hufsa]

I fail to understand how iron in a red house brick could be considered water-soluble

Im going to go out on a limb and say that he was suggesting that those selling these products are being "economical" with the truth when they say their substrate (or other product) is "rich in iron".
Yes the substrate/product is technically made up of this substance, but not in a form that is actually useful to plants or usable the way the seller wants the buyer to think it is.

An example that kind of fits: I am made up of a majority of water, but im still not a good thing to use to water a dry plant.

Seachem Flourite is technically "iron rich" but its still not a nutritious substrate for plants

 

[dw1305]

Hi all,

Hi @dw1305

I fail to understand how iron in a red house brick could be considered water-soluble. If this was the case, wouldn't our houses be slowly eroded whenever we get a downpour of rain?

You are right @jaypeecee, neither iron rich substrate or brick are soluble.

If you want an analogy it is analogous to nitrogen (N). The atmosphere is nitrogen rich (70%) but that nitrogen is unavailable to nearly all organisms all the time it is N2 gas.

If you can break the triple bond between nitrogen atoms new compounds form easily, but away from a limited range of circumstances it will remain as N2 gas for all of eternity.

Exactly the same for iron (Fe) oxides and hydroxides, insoluble in all but exceptional circumstances.

Cheers Darrel

 

[_Maq_]

away from a limited range of circumstances it will remain as N2 gas for all of eternity.

Exactly the same for iron (Fe) oxides and hydroxides, insoluble in all but exceptional circumstances.

True, but we have bacteria, fungi, and even plants' roots which may exude compounds which create those "exceptional circumstances".
I'm rather ambiguous about these 'iron rich' substrates. Their vendors rely on the fact that few hobbyists know anything about iron's behaviour. Most laterites contain iron in huge excess for plants' consumption. They are much more important as sorbents, both in good & bad ways.

 

[jaypeecee]

If you want an analogy it is analogous to nitrogen (N). The atmosphere is nitrogen rich (70%) but that nitrogen is unavailable to nearly all organisms all the time it is N2 gas.

Hi @dw1305

It's probably best that we limit the discussion to iron. Nitrogen can form the azide ion (N3-) and I seem to recall N3 being mentioned in school chemistry so my knowledge of it is now (almost) zilch.

Exactly the same for iron (Fe) oxides and hydroxides, insoluble in all but exceptional circumstances.

These iron compounds may be soluble in water, solubility simply depending on the water pH.

JPC

 

[dw1305]

Hi all,

These iron compounds may be soluble in water, solubility simply depending on the water pH.

Not once they are <"ferric oxides and ferric hydroxides">, they will only release their iron as ions <"in exceptional circumstances">.

The <"haematite that supplies most of the world's steel"> is Pre-Cambrian in age. If billions of years of rainfall haven't dissolved it? You know <"that it isn't soluble"> in aerobic conditions.

It's probably best that we limit the discussion to iron.

I'll give <"you another example">, from a thread that we both contributed to, quartz (SiO2), it contains silicon (Si) but that silicon will remain as silicon dioxide for all of eternity.

cheers Darrel

 

[jaypeecee]

Hi @dw1305

Ah, the penny has finally dropped! I knew that my brain was beginning to atrophy. And, here is the proof.

JPC

 

[jaypeecee]

Not once they are <"ferric oxides and ferric hydroxides">, they will only release their iron as ions <"in exceptional circumstances">.

Hi @dw1305

What? More? Surely not!

I need to think this through again because it just dawned on me that such "exceptional circumstances" may include underwater where redox/ORP is very likely to be sub-zero mV*. An actual experiment with tests would possibly be helpful. I don't have a problem being proven that I've got my facts wrong. I just like to get to the facts.

* i.e. anoxic/anaerobic

JPC

 

[dw1305]

Hi all,

it just dawned on me that such "exceptional circumstances" may include underwater where redox/ORP is very likely to be sub-zero mV*

That is it, strongly acidic, reducing conditions will make iron (Fe) available. <"Redox Transformations of Iron at Extremely Low pH: Fundamental and Applied Aspects">.

There is a lot of academic research on iron and flooding of terrestrial crops, because under flooded conditions soil may become anoxic and iron may go from being unavailable to available. Although iron is an essential micronutrient for plants it is also toxic at higher levels of availability.

.....Iron toxicity is relatively rare, but the symptoms include bronzed and striped leaves. These effects are the result of excess Fe-hydroxyl radicals disrupting cellular functions. Due to the importance of maintaining iron concentrations within safe ranges in plant tissues, the whole process of iron uptake into roots (i.e., the movement from roots to shoots and storage and release within plant cells) is highly regulated......*

The biochemistry of iron in soils is complex, which is why a simple statement of total iron content doesn't tell us anything about availability.

You can think about it like potential and kinetic energy. In oxidising conditions "total iron" is a large boulder on a flat surface, it has potential energy, but not kinetic energy. You need a fairly large change of circumstances for that potential to become kinetic energy, if that makes sense?

This is a good review <"https://acsess.onlinelibrary.wiley.com/doi/10.1002/crso.20019">. "Iron Availability and Management Considerations: A 4R Approach"

......... Iron concentration can be present at 50,000 times the crop’s annual demand, but factors that affect availability limit utilization. The main source of iron in soils for use by plants comes from secondary oxides absorbed or precipitated onto soil mineral particles and iron–organic matter complexes.......Soil pH and water-filled pore space will significantly affect the form of iron present. In aerated soils, iron is readily oxidized to its ferric state and forms a group of highly insoluble ferric oxides and hydroxide minerals, such as goethite (FeOOH) and hematite (Fe2O3)

*Quotes are from <"Iron Availability and Management Considerations: A 4R Approach">

cheers Darrel

 

[jaypeecee]

Hi @dw1305

I feel like Archimedes must have done when he jumped out of his bath shouting 'Eureka'!

Thanks for confirming my hunch.

JPC