# Ideal soil type?



## penfold (Dec 7, 2010)

So I'm setting up my first planted tank (a 75g pond in my greenhouse), and I've decided to go with a natural, low maintenance method. I've read most of Diana's book, but I'm wondering about the soil. With terrestrial soils there is an ideal composition in terms of sand, silt and clay. But this is due mainly to drainage and resultant aeration. Since there is no drainage in a submersed substrate, does the composition really matter that much?

For example, here is some sifted soil from my backyard.










Our soil is classified as a silty clay loam, and a shake test confirms that there is only about 10% sand. Would there be any benefit to adding some fine sand to this soil, or is that unnecessary?


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## JeffyFunk (Apr 6, 2006)

penfold said:


> So I'm setting up my first planted tank (a 75g pond in my greenhouse), and I've decided to go with a natural, low maintenance method. I've read most of Diana's book, but I'm wondering about the soil. With terrestrial soils there is an ideal composition in terms of sand, silt and clay. But this is due mainly to drainage and resultant aeration. Since there is no drainage in a submersed substrate, does the composition really matter that much?


I don't believe that the exact composition matters that much in terms of sand, silt and clay. In an El natural tank using a soil substrate and no CO2 injection, the silt and clay particles are an important nutrient source for plant roots and the presence of some organic matter is important as well so that it can decompose and provide a carbon source to the plants (I think having too much organic matter can rob the aquarium of oxygen due to the decomposition process, though - but I don't know that for sure). The soil you have pictured looks like a good candidate to try in an aquarium. Most people focus on other aspects of the soil, such as removing all large particulate matter such as rocks and twigs and the like.



penfold said:


> Our soil is classified as a silty clay loam, and a shake test confirms that there is only about 10% sand. Would there be any benefit to adding some fine sand to this soil, or is that unnecessary?


As far as I know, there have been no reports of increased growth from the addition of sand to a soil substrate. I have read accounts of increased growth of some of the more difficult cryptocoryne species w/ the addition of sand to the substrate, but I think they are the exception and not the rule. The important part is that a soil substrate provide a good nutrient source to your plants that, say, plain gravel does not have.


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## penfold (Dec 7, 2010)

Thanks. I figured that was the case. I'll look into substrates for Cryptocoryne, but it sounds like my soil will work pretty well as is.


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## potatoes (Jun 25, 2010)

Your soil looks good as long as you haven't used fertilizers or pesticides where you collected it from. I would soak it a couple times first. In the end, the organic matter will be the decomposing fish waste and fish food, which will act as the fertilizer and co2 source, so perfect soil composition isn't that important as long as it is not in the extremes, which yours dose not appear to be.


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## Michael (Jul 20, 2010)

+1 for JeffyFunk's comments. One thing you might try is a jar test with your soil. Put a small handful in a jar of water, put the lid on and shake it. Let it sit and see how long it takes for the particles to settle out. Clay can remain in suspension for a long time; if your soil has this problem, but prepared to put a good cap of coarse sand or aquarium gravel on it.


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## penfold (Dec 7, 2010)

Potatoes, the soil was collected from a forested area of my backyard, so there shouldn't be any contaminants. What is the reasoning behind soaking the soil? It would take a long time to dry it this time of year, so I'd prefer to skip that step if possible.

Michael, I did the shake test and got a small amount of clay that took a day or two to settle out. I'll use a good inch or so of gravel to cap it, and some mechanical filtration to clear things up.


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## Michael (Jul 20, 2010)

Sounds like it will work well! Please let us see photos of your greenhouse pond.

--Michael


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## penfold (Dec 7, 2010)

Will do, thanks.


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## JeffyFunk (Apr 6, 2006)

penfold said:


> What is the reasoning behind soaking the soil? It would take a long time to dry it this time of year, so I'd prefer to skip that step if possible.


The reason some suggest you soak your soil before hand is to "Mineralize" the soil. The following thread will explain more about the process of mineralization:

http://www.aquaticplantcentral.com/...-mineralized-soil-substrate-aaron-talbot.html

In essence, mineralization is the process of taking soil (top soil usually) and (1) physically removing large objects from it (like pieces of bark, stones, etc), (2) removing all of the organic material from it by repeatedly soaking & drying it and (3) fortifying it through the addition of clay (for Fe), dolomitic lime (for Ca & Mg) and potash (for K).

Mineralization of soil isn't necessary (I've had great luck w/out mineralizing soil), but is a great thing to do if you have the time.


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## penfold (Dec 7, 2010)

Ok, I've read about mineralization. I thought maybe there was still a reason to soak when using Diana's method.

If I could do it outdoors, I'd consider mineralization. But since it's winter now, I think I'll just lay it down as is, plant heavily, and hope for the best.

Thanks, guys.


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## Molch (Nov 10, 2010)

JeffyFunk said:


> Mineralization of soil isn't necessary (I've had great luck w/out mineralizing soil), but is a great thing to do if you have the time.


but this I don't understand - if it isn't necessary, why bother? What advantage do you gain from it?


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## JeffyFunk (Apr 6, 2006)

Molch said:


> but this I don't understand - if it isn't necessary, why bother? What advantage do you gain from it?


For the reasons I stated, the mineralization is a great thing to do if you have the time. The effects of soil mineralization are probably of greater benefit in a high tech aquarium where the greater nutrient density of the mineralized soil helps plant growth and reduces the need for supplemental nutrient dosing, but are also beneficial to a low tech, non-CO2 injected planted aquarium as well (more nutrients in the substrate that are available only to the plants is usually a good idea).

I also think mineralization also has another effect that is beneficial to all planted aquariums: consistency. At our PAPAS (Pittsburgh area planted aquarium society) meetings, some people have complained that when setting up a soil substrate, they experience green water, probably due to the release of nutrients from the soil into the water column. Other people do not report having any issues with using a soil substrate. Some people report that their soil substrate "burps", releasing pockets of gas every so often. All of these issues seem to be non-existent when using a mineralized soil substrate in our (limited) experiences.


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## Diana K (Dec 20, 2007)

The other thing that mineralizing does is to aggregate the clay particles together. They are still clay, so you get the benefits of the high CEC, but when they are stuck together they do not cloud the water so much. 
Handle the soil gently so you do not break apart the particles that are starting to clump together. 

If you know ahead of time that the soil is lacking in some nutrients then materials that release those minerals can be placed on the floor of the tank, then the soil placed over that. For example, laterite for Iron. Coral sand for several minerals. 

The reason you want a looser, more open substrate is so the water can flow through it. If the water cannot flow through it there might develop some anaerobic pockets. Thriving plants will add some oxygen into the substrate, but they are not everywhere in the tank. 

In a sample of soil shaken in a jar:
Half or more of the soil should settle out in less than 1 minute. This is the coarser to finer sand. 
Another half should settle out in 2 minutes. This is silt. 
The water ought to be fairly clear (maybe a bit of a haze) in 2 hours. The larger clay particles have settled out. 
If the water is still cloudy the next day it will not really settle well in the tank, either. This is coloidal clay. So fine the brownian motion of the water molecules is keeping it suspended. 

End result:
Sand: 50% or more
Silt: 25% 
Clay: not over 10% (and it should have pretty much all settled out in the first 2 hours in the jar test)

Note that I am saying sand as a component of the soil. Do not start with a bag of sand and add some potters clay and call it good. The particles will separate by size and your tank will end up in layers. 
The sand-silt-clay blend that is found in natural soils has been there a while, and the parts will not separate.


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## Molch (Nov 10, 2010)

can mineralized soils be bought, or does one have to make them oneself as per the instructions above?


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