# Can laterite be used as a substrate ?



## tinman84 (May 8, 2012)

i know laterite can be used as a mix to fertilize plants 


the question is can i use a lot of laterite as a substrate by iteslf ? 

so substrate would be laterite only and nothing else ?


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## Michael (Jul 20, 2010)

Yes, you can use laterite as the only substrate.

But you have a mistaken impression that laterite has nutrients (fertilizer) for plants. It doesn't, except for the red colored laterite which contributes the minor nutrient iron. What laterite does have is high cation exchange capacity (CEC). This means it can absorb nutrients from the water, or from other materials or fertilizers in the substrate. It then holds the nutrients until plant roots grow into it, and extract the nutrients by their own chemical means. It can do this over and over again; it doesn't wear out.

So if you use laterite alone, you will need fertilizers of some sort. My favorite method is to combine the laterite with soil, but there are lots of other ways to do it.


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## K Randall (Nov 23, 2004)

I would NOT use laterite as a sole substrate. It is clay, and will make a HUGE mess in the water. It does make a very acceptable media for growing plants when mixed into the bottom layer of gravel, then capped with plain quartz gravel. I also like to throw a handful of peat into it.

As Michael said, laterite substrates a very long lasting as long as you fertilize regularly. I have one 75G gravel/laterite tank that while it has been reset several times, hasn't had the substrate REPLACED in over 15 years, and it still grows plants well. 

The limiting factor in the tank is that eventually it gets root bound, just as a potted plant does. At that point, I remove the plants from about 1/3 of the tank, divide, root trim and replace. I will do 1/3 per month until the tank is done, at which point it grows really well again for at least another year. One thing to remember is that a set-up like this develops a lot of its own organic material in the substrate over time, both as mulm settles into it, and as plants are trimmed or uprooted, leaving part of the root system behind.

I've included photos showing how to set up a laterite substrate so that you won't have cloudy water, plus a couple of photos of that tank over the years. This is not an "aquascaped" tank, just a pleasant, planted fish tank. One of the photos was dated 2003, and while I don't have a date for the other photo, it was probably something like 2005. The tank is still running now, with no change in substrate. (I still have some of those fish in there too!


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## OTPT (Sep 27, 2010)

^
^
Good growth indeed!


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## tinman84 (May 8, 2012)

My laterite isnt that fine .. i alrady have it in the tank and water isnt that cloudy at all ... 

i dont wanna mix it with other subtrates as i like to create heaps and mountains and its for a fluval nano 8 gallon 

so i can really use laterite as its own substrate then i can just dose water and then the substrate becomes really rich in nutrients i guess ...right ?


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## Michael (Jul 20, 2010)

Right, and instead of dosing the water you can use root tabs or some other type of substrate fertilizer.


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## K Randall (Nov 23, 2004)

tinman84 said:


> My laterite isnt that fine .. i alrady have it in the tank and water isnt that cloudy at all ...
> 
> i dont wanna mix it with other subtrates as i like to create heaps and mountains and its for a fluval nano 8 gallon
> 
> so i can really use laterite as its own substrate then i can just dose water and then the substrate becomes really rich in nutrients i guess ...right ?


Not sure what you have that you are calling laterite, but laterite IS clay. If what you have isn't clouding the water, I doubt it's really laterite. Part of what gives laterite the high CEC it has is the fine particles. Larger particles that won't cloud the water also have less surface area to "grab" and bind nutrients.


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## Michael (Jul 20, 2010)

Yes, laterite is clay, and it exists in "fired" and "unfired" forms. Fired laterite (also called calcined, metamorphic, or sintered) has been subjected to natural or artificial heat until it becomes hard and not easily broken down. This is the same process that produces ceramics from soft wet clay. Fired laterite retains its porosity and high CEC.

Examples of fired or metamorphic laterite include Flourite (natural processes), Turface, Soil Master Select, and various other trade names, all baked in a kiln. Unfired laterite includes cat litter, Oil-Dri, Safe-T-Sorb (a.k.a. fuller's earth), and others.

I have used both fired and unfired laterite in my tanks as a cap for soil and as an admixture for soil in the lower substrate. Fired laterite, when washed, produces very little cloudiness. Unfired laterite, also washed, produces more cloudiness. But this subsides in a day or two with adequate filtration.

This is in new tanks. In mature tanks the flocculating effect of biofilm makes both forms of laterite even less likely to cause cloudiness.


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## BruceF (Aug 5, 2011)

Some of these people are even old enough to remember Dupla.


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## DaTrueDave (Dec 28, 2003)

Michael said:


> Examples of fired or metamorphic laterite include Flourite...


I know that Flourite is a fired clay, but I didn't think it was a laterite?


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## K Randall (Nov 23, 2004)

Fluorite, as far as I have been told, is NOT laterite, and while it can cloud an aquarium if not handled properly, can also be installed, all by itself, with no cloudiness. And yes, I am certainly old enough to not only remember, but to have used Dupla laterite , but I don't believe that was fired either. It behaved like clay.

BTW, even the clay types of laterite, when properly installed as an underlayment, and then with the tank filled slowly, don't need to cloud the water. And once they've been in use for a while, you can pull even huge Echinodorus up with impunity. The water will muck up for a little while, but will clear by the next day.


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## Michael (Jul 20, 2010)

SeaChem's web site makes it sound like Flourite is not laterite, but other authorities have a different opinion. We need a geologist to settle the question.

This is a pet peeve: manufacturers of aquarium products who do not tell you what is actually in their mechandise.


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## DaTrueDave (Dec 28, 2003)

Michael said:


> We need a geologist to settle the question.


I don't think we do.

I just spent a bit of time researching this, and the problem is that the word "laterite" is fairly imprecise. It can mean "a red soil near the earth's surface". It can mean "an aluminum and/or iron-rich soil". It can mean "red clay". It can mean "iron rich clay". It can mean "soil subjected to a prolonged process of chemical weathering which produces a wide variety in the thickness, grade, chemistry and ore mineralogy".

Given that the word itself can have such different meanings, I think it's obvious why different people are going to have different ideas on whether or not something is laterite. Even the geological definition is pretty broad and subjective.


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## Michael (Jul 20, 2010)

Most of the things I've read tend to use the broader definition, by which Flourite is laterite. SeaChem understandably likes to make a distinction between the form of laterite in their product and other forms which are not as easy to use in aquaria.


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## Skizhx (Oct 12, 2010)

Redart clay also seems like a solid alternative to laterite. Similar in iron content and CEC.


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