Aquatic Plant Forum banner

How-To: Mineralized Soil Substrate, by Aaron Talbot

678K views 601 replies 207 participants last post by  Firestorm1976 
#1 · (Edited by Moderator)
How-To: Mineralized Soil Substrate


Over the years dedicated aquatic plant hobbyists have developed many different methods to maintain vibrant freshwater flora. After having tried almost all of the popular fertilization techniques, I have finally found one that produces consistently healthy aquatic plants. That fertilization method imparts essential nutrients by using mineralized topsoil as a substrate.

When I joined the Greater Washington Aquatic Plant Association about four years ago, I attended my first official meeting at the home of Sean Murphy. Sean is a Fisheries Biologist by trade and has been employing mineralized soil in his planted aquariums for nearly two decades now. He developed a "recipe" for the soil substrate during his collegiate studies of wetlands soils. It is his recipe that I have recently begun using with great success.

Using topsoil or potting soil as a substrate is not a new idea. Aquarists have been using this method to grow healthy aquatic plants for decades. However, this method does seem to pose some problems, namely algae outbreaks resulting from light intensity that is too strong. This is especially true when you first set up your aquarium with this type of substrate. The algae likely results from the excess nutrients that decomposing organic materials release in the soil. The decomposing organic materials are not bio-available to the aquatic plants. As the tank matures, the algae dissipate slowly as the organics in the soil finish breaking down.

Mineralizing the soil beforehand helps to speed the breakdown of organic materials in the soil. In turn the mineralized soil will help shorten the initial algae outbreak period that many aquarists experience when using a soil substrate. Soil mineralization occurs from exposing bacteria, enzymes and other soil microbes to oxygen in a moist environment. The microbes break down the organic materials in the soil into bio-available minerals. As an added bonus these new bio-available forms of nutrients are generally only available to plants and not to algae.

There are a few other components to the mineralized soil recipe. Clay provides a source of iron. The clay also serves to bind with the soil as a flocculating agent. When plants are uprooted or disturbed, the added clay will help the soil to settle back to the bottom of the tank. Adding Dolomite to the base of the substrate will provide plants with the necessary calcium and magnesium they need for healthy growth. The calcium and magnesium in the dolomite will also help to keep the soil from becoming too acidic. Lastly, add soluble potash for an initial potassium source.

It is still possible to use pressurized CO2 and high lighting with this method of fertilization. I have setup four tanks using this method and all of them have been high-tech setups using CO2 and high lighting. I rarely ever have to dose any supplements save for the occasional dose of potassium. Use caution when dosing and dose very little amounts at a time.

I've composed a list of materials and step-by-step instructions for those readers who would like to try the mineralized soil substrate method.

Materials Needed

Cheap topsoil
Pottery clay
Dolomite
Muriate of potash
Fine gravel or coarse sand
• Large container for soaking soil
• Screen made from scrap wood and chicken wire
• Nylon screening material
• Large plastic tarp

Step 1 - Purchase and Rinse the Topsoil

Open the bag of topsoil and distribute in the container of your choice for soaking purposes. I use large Rubbermaid containers that are readily available from any mega-mart. You will want to use cheap topsoil and not potting soil. Potting soil has additives to avoid such as fertilizers, vermiculite and peat moss.
Fill the tub with water so the water level is a few inches above the top of the soil. I like to stir it around a bit to help break up any big clumps and evenly distribute the water. Let this soak for a day or two. Come back and slowly dump the water off of the top. Now add in more water so the soil is well covered. This water changing process helps to "rinse" the soil of any possible fertilizers or other harmful water soluble chemicals.

Step 2 - Allow the Topsoil to Dry

Pour the excess water out of the container as you did when changing the water. Lay out the large plastic tarp, preferably in direct sunlight. Dump out the muddy soil and spread it relatively thin over the tarp. Allow the soil to dry completely. This can take a day or two and depends greatly on how warm the temperature is where you are drying the soil. This part of the process could be done indoors. Though due to its messy nature, I suggest doing it outdoors if possible. When the soil is completely dry, add it back into the soaking container.
The drying process is the part that allows the microbes in the soil to begin mineralizing the nutrients. Exposing it to air oxygenates the soil.

Step 3 - Repeat the Rinsing and Drying Cycles

Repeat steps 1 and 2 three to four times. Repeating the steps is necessary to further mineralize the soil and remove any lingering fertilizers. The soil mineralizes the most during the time while it is still moist and exposed to air on the large tarp. By soaking it over again we reintroduce the needed moisture for this process to take place. When the soil is near fully mineralized it will have a very grainy texture. Another way to tell that the soil is ready is by smell. There will be virtually no smell coming from the soil once it is mineralized.


Mineralized Topsoil

Step 4 (optional) - Sift the Soil to Remove Debris

Screening the soil can help to remove any large organic materials that the short mineralization process employed thus far cannot remove. I have setup tanks where I skipped Step 4 and others where I used it. I have found that adding this step to the process helps to further eliminate algae issues after a tank is newly setup.
You can use a wooden frame with chicken wire stapled to four sides. Then place nylon screening material overtop. Place a few handfuls of soil on top and gently push the soil across the surface of the screen. Make sure to put a container underneath to catch the sifted soil. Below is a picture of the sticks, leaves and stones that can be removed during this step. The resulting sifted soil will feel like airy sand.


Screening Setup

Step 5 - Add the Clay

Now that you have a mineralized soil to use as the substrate, you will want to add in the aforementioned clay. Estimate how much clay you will need so that the resulting mixture of soil and clay is about 5% to 10% clay. If you prefer measurements I use about ¼ of a pound of clay per square foot of tank bottom.
To add the clay you soak it in a container of water to help emulsify it and make it easier to incorporate into the soil. A second option to add clay is to dry the clay in the open air and then crush it into a powder and add it to the soil. In either case you will want to eventually add enough water to the mixture to form a nice runny mud.


Mineralized Soil Mud with Clay Added

Step 6 (optional) - Create an Aesthetic Border

Now comes the fun part of setting up the aquarium. Add the gravel of your choice just along the front and side edges of the aquarium bottom. Wet it just enough that it holds a slope and press it up against the sides. Doing this step ensures that we will not see the different layers of substrate when viewing the tank from the front and sides. In this instance I have chosen to use 3M Colorquartz T-Grade Black Sand as a substrate top layer. I prefer this coarse sand for many reasons. It is very dense and holds a slope for a long period of time. The finer granules also allow for easy planting.


Sand Border

Step 7 - Add the Dolomite and Muriate of Potash

Sprinkle a light dusting of both the dolomite and muriate of potash on the bottom glass of the tank. The bottom of the glass should still be somewhat visible.


Sprinkling of Dolomite and Potash

Step 8 - Add the Mineralized Mud

Fill in the borders you've created with the runny mud mixture of mineralized soil and clay. This layer should be anywhere from ½" to 1" deep.


Mineralized Mud Added

Step 9 - Top With Gravel

Cover the mud with more of the same border gravel from step 6. If you skipped step 6 then simply cover over the mud with the gravel of your choice. Cover the mud by about 1" in the front to 2" in the back of the tank to create a nice sloping substrate effect.


Gravel Top Layer Added

Step 10 - Slowly Fill the Aquarium and Begin Planting

Begin planting and filling the aquarium as you would any other planted aquarium. Use caution when filling the tank with water. Go slowly to avoid disturbing the substrate and uncovering the soil.

The End Product

I hope this has inspired you to try something new. I know I had wanted to try mineralized soil for some time after seeing Sean's beautiful aquariums. I finally got up the courage to set up a small 20 gallon tank last year and now I'm hooked. With a little patience and trial and error, I think you'll be pleased with the results.


My ADA 90-P aquarium with a mineralized soil substrate


My AGA 75 gallon aquarium with a mineralized soil substrate
 
See less See more
9
#581 ·
Very good idea! I'm not sure why it was considered important to add clay to mineralized soil, so I'm not sure if STS meets the need. As I recall, it was iron-rich clay that was recommended, but Diana Walstad has pointed out that ordinary dirt contains a significant amount of iron anyway. (I'm too lazy to read 58 pages here to find out why the clay.)
 
#582 ·
I don't remember Diana ever mentioning adding clay. At least I can't find it. But she does discuss problems with iron toxicity. Seems like that kinda just popped up somewhere about adding red clay as an iron source.
Also, I'm pretty certain montmorillonite clay (STS/OilDri) is not a source of iron. STS is used in the substrate to bind nutrients because of its high CEC. Pottery clay and montmorillonite clay are two different materials to the best of my knowledge.
 
#585 ·
I use VERY small amounts of powdered calcium bentonite every few days. Like barely a pinch in a 10 gallon tank just added to water. Supposedly it absorbs toxins and provides a few minerals among other things. Koi breeders have been using it for years. (https://allnaturalpetcare.com/blog/...tmorillonite-clay-for-pond-and-aquarium-fish/). I don't think it has any CEC value. It has a totally different purpose and form than STS or OilDri and you would never use it in the volume that we do STS! STS or OilDri are very large particles that take a very, very long time to dissolve, if ever. The product you are referring to is a very finely ground powder as people consume the food grade type (which is what I have). You really can't compare the 2 products.
 
#587 · (Edited)
I don't think it has any CEC value. It has a totally different purpose and form than STS or OilDri and you would never use it in the volume that we do STS! STS or OilDri are very large particles that take a very, very long time to dissolve, if ever. The product you are referring to is a very finely ground powder as people consume the food grade type (which is what I have). You really can't compare the 2 products.
STS & Oildri goes through a process of drying, shaped, sized, and firing (like pottery but not exactly) so they don't dissolve in water. Bentonite & montmorillonite clay are the same stuff.
The powdered form has more surface area than the baked form.
 
#592 ·
Clay mixed in the substrate promotes plant growth by increasing the cation exchange capacity (CEC) of the soil, helping roots to efficiently utilize soil nutrients.

There are a few other components to the mineralized soil recipe. Clay provides a source of iron. The clay also serves to bind with the soil as a flocculating agent. When plants are uprooted or disturbed, the added clay will help the soil to settle back to the bottom of the tank.
I'm still not sure about the sodium vs. calcium question, though.

Sent from my Pixel 3a using Tapatalk
 
#593 ·
Does anyone here keep invertebrates? I've given this recipe a go and it appears to have created a toxic environment for my shrimp and nerite snails. Several batches have died, even after isolating one variable after another. Meanwhile, I'm keeping another dirted tank, utilizing the same tap water and many of the same plants, with zero issues.

I raised this issue on the El Natural forum, and Diana Walstad mentioned: "Many clays contain aluminum. The clay may be fine by itself, but when you mix it with an organic soil, the organic matter can solubilize the aluminum oxides and release toxic aluminum into the water. Invertebrates are particularly sensitive to heavy metals, which includes aluminum." She also was concerned about using solid potash.

I've spoken with two others who have used this mineralization method and cannot keep invertebrates in those tanks, despite being able to keep them in other tanks. It seems quite likely that something toxic is being leached from the soil substrate.

I'm very curious if anyone else has experienced an issue like this using the mineralization method suggested in this post.
 
#596 ·
Does anyone here keep invertebrates? I've given this recipe a go and it appears to have created a toxic environment for my shrimp and nerite snails. Several batches have died, even after isolating one variable after another. Meanwhile, I'm keeping another dirted tank, utilizing the same tap water and many of the same plants, with zero issues.

I raised this issue on the El Natural forum, and Diana Walstad mentioned: "Many clays contain aluminum. The clay may be fine by itself, but when you mix it with an organic soil, the organic matter can solubilize the aluminum oxides and release toxic aluminum into the water. Invertebrates are particularly sensitive to heavy metals, which includes aluminum." She also was concerned about using solid potash.

I've spoken with two others who have used this mineralization method and cannot keep invertebrates in those tanks, despite being able to keep them in other tanks. It seems quite likely that something toxic is being leached from the soil substrate.

I'm very curious if anyone else has experienced an issue like this using the mineralization method suggested in this post.
Thank you so much for this valuable post. It's very reasonable that there are still people who show how many of these "miracle recipes" work out in reality.
I love shrimp and have a lot of them, I can't imagine what a tragedy it would be to see beautifully colored populations die just because some people only list the positive aspects of their experiments!
 
#594 ·
How-To: Mineralized Soil Substrate


Over the years dedicated aquatic plant hobbyists have developed many different methods to maintain vibrant freshwater flora. After having tried almost all of the popular fertilization techniques, I have finally found one that produces consistently healthy aquatic plants. That fertilization method imparts essential nutrients by using mineralized topsoil as a substrate.

When I joined the Greater Washington Aquatic Plant Association about four years ago, I attended my first official meeting at the home of Sean Murphy. Sean is a Fisheries Biologist by trade and has been employing mineralized soil in his planted aquariums for nearly two decades now. He developed a "recipe" for the soil substrate during his collegiate studies of wetlands soils. It is his recipe that I have recently begun using with great success.

Using topsoil or potting soil as a substrate is not a new idea. Aquarists have been using this method to grow healthy aquatic plants for decades. However, this method does seem to pose some problems, namely algae outbreaks resulting from light intensity that is too strong. This is especially true when you first set up your aquarium with this type of substrate. The algae likely results from the excess nutrients that decomposing organic materials release in the soil. The decomposing organic materials are not bio-available to the aquatic plants. As the tank matures, the algae dissipate slowly as the organics in the soil finish breaking down.

Mineralizing the soil beforehand helps to speed the breakdown of organic materials in the soil. In turn the mineralized soil will help shorten the initial algae outbreak period that many aquarists experience when using a soil substrate. Soil mineralization occurs from exposing bacteria, enzymes and other soil microbes to oxygen in a moist environment. The microbes break down the organic materials in the soil into bio-available minerals. As an added bonus these new bio-available forms of nutrients are generally only available to plants and not to algae.

There are a few other components to the mineralized soil recipe. Clay provides a source of iron. The clay also serves to bind with the soil as a flocculating agent. When plants are uprooted or disturbed, the added clay will help the soil to settle back to the bottom of the tank. Adding Dolomite to the base of the substrate will provide plants with the necessary calcium and magnesium they need for healthy growth. The calcium and magnesium in the dolomite will also help to keep the soil from becoming too acidic. Lastly, add soluble potash for an initial potassium source.

It is still possible to use pressurized CO2 and high lighting with this method of fertilization. I have setup four tanks using this method and all of them have been high-tech setups using CO2 and high lighting. I rarely ever have to dose any supplements save for the occasional dose of potassium. Use caution when dosing and dose very little amounts at a time.

I've composed a list of materials and step-by-step instructions for those readers who would like to try the mineralized soil substrate method.

Materials Needed

Cheap topsoil
Pottery clay
Dolomite
Muriate of potash
Fine gravel or coarse sand
• Large container for soaking soil
• Screen made from scrap wood and chicken wire
• Nylon screening material
• Large plastic tarp

Step 1 - Purchase and Rinse the Topsoil

Open the bag of topsoil and distribute in the container of your choice for soaking purposes. I use large Rubbermaid containers that are readily available from any mega-mart. You will want to use cheap topsoil and not potting soil. Potting soil has additives to avoid such as fertilizers, vermiculite and peat moss.
Fill the tub with water so the water level is a few inches above the top of the soil. I like to stir it around a bit to help break up any big clumps and evenly distribute the water. Let this soak for a day or two. Come back and slowly dump the water off of the top. Now add in more water so the soil is well covered. This water changing process helps to "rinse" the soil of any possible fertilizers or other harmful water soluble chemicals.

Step 2 - Allow the Topsoil to Dry

Pour the excess water out of the container as you did when changing the water. Lay out the large plastic tarp, preferably in direct sunlight. Dump out the muddy soil and spread it relatively thin over the tarp. Allow the soil to dry completely. This can take a day or two and depends greatly on how warm the temperature is where you are drying the soil. This part of the process could be done indoors. Though due to its messy nature, I suggest doing it outdoors if possible. When the soil is completely dry, add it back into the soaking container.
The drying process is the part that allows the microbes in the soil to begin mineralizing the nutrients. Exposing it to air oxygenates the soil.

Step 3 - Repeat the Rinsing and Drying Cycles

Repeat steps 1 and 2 three to four times. Repeating the steps is necessary to further mineralize the soil and remove any lingering fertilizers. The soil mineralizes the most during the time while it is still moist and exposed to air on the large tarp. By soaking it over again we reintroduce the needed moisture for this process to take place. When the soil is near fully mineralized it will have a very grainy texture. Another way to tell that the soil is ready is by smell. There will be virtually no smell coming from the soil once it is mineralized.


Mineralized Topsoil

Step 4 (optional) - Sift the Soil to Remove Debris

Screening the soil can help to remove any large organic materials that the short mineralization process employed thus far cannot remove. I have setup tanks where I skipped Step 4 and others where I used it. I have found that adding this step to the process helps to further eliminate algae issues after a tank is newly setup.
You can use a wooden frame with chicken wire stapled to four sides. Then place nylon screening material overtop. Place a few handfuls of soil on top and gently push the soil across the surface of the screen. Make sure to put a container underneath to catch the sifted soil. Below is a picture of the sticks, leaves and stones that can be removed during this step. The resulting sifted soil will feel like airy sand.


Screening Setup

Step 5 - Add the Clay

Now that you have a mineralized soil to use as the substrate, you will want to add in the aforementioned clay. Estimate how much clay you will need so that the resulting mixture of soil and clay is about 5% to 10% clay. If you prefer measurements I use about ¼ of a pound of clay per square foot of tank bottom.
To add the clay you soak it in a container of water to help emulsify it and make it easier to incorporate into the soil. A second option to add clay is to dry the clay in the open air and then crush it into a powder and add it to the soil. In either case you will want to eventually add enough water to the mixture to form a nice runny mud.


Mineralized Soil Mud with Clay Added

Step 6 (optional) - Create an Aesthetic Border

Now comes the fun part of setting up the aquarium. Add the gravel of your choice just along the front and side edges of the aquarium bottom. Wet it just enough that it holds a slope and press it up against the sides. Doing this step ensures that we will not see the different layers of substrate when viewing the tank from the front and sides. In this instance I have chosen to use 3M Colorquartz T-Grade Black Sand as a substrate top layer. I prefer this coarse sand for many reasons. It is very dense and holds a slope for a long period of time. The finer granules also allow for easy planting.


Sand Border

Step 7 - Add the Dolomite and Muriate of Potash

Sprinkle a light dusting of both the dolomite and muriate of potash on the bottom glass of the tank. The bottom of the glass should still be somewhat visible.


Sprinkling of Dolomite and Potash

Step 8 - Add the Mineralized Mud

Fill in the borders you've created with the runny mud mixture of mineralized soil and clay. This layer should be anywhere from ½" to 1" deep.


Mineralized Mud Added

Step 9 - Top With Gravel

Cover the mud with more of the same border gravel from step 6. If you skipped step 6 then simply cover over the mud with the gravel of your choice. Cover the mud by about 1" in the front to 2" in the back of the tank to create a nice sloping substrate effect.


Gravel Top Layer Added

Step 10 - Slowly Fill the Aquarium and Begin Planting

Begin planting and filling the aquarium as you would any other planted aquarium. Use caution when filling the tank with water. Go slowly to avoid disturbing the substrate and uncovering the soil.

The End Product

I hope this has inspired you to try something new. I know I had wanted to try mineralized soil for some time after seeing Sean's beautiful aquariums. I finally got up the courage to set up a small 20 gallon tank last year and now I'm hooked. With a little patience and trial and error, I think you'll be pleased with the results.


My ADA 90-P aquarium with a mineralized soil substrate


My AGA 75 gallon aquarium with a mineralized soil substrate
I am definitely going to try this, as I am going to try my first dirted tank with a 29G. I have seen some people also add Black Kow or worm casings . I think they said that is for nitrogen? Is anything like that needed or would it be a bad idea to add that. I am using the Father Fish method and capping 1 inch of dirt with 3-4 inches of BDBS
 
#597 ·
can i use potassium chloride powder instead of potash? i googled "potash" its referred as KCL/potassium chloride but its look different from the image , i have potassium chloride its white crystalized powder like a salt and easily dissolved in water while i the image of potash its red granulated not sure its dissolved easily or not , is it still the same thing or it contain different nutrients?

is adding clay or laterite necessary? its hard to find pottery clay here , i can buy granulated laterite but not really cheap..the other option is red soil not sure if it will give same nutrients like laterite or clay
 
#602 ·
Aaron, thank you so much for this wonderful and highly educational post!
I have a few questions, if I may. I can't find organic top soil anywhere, it just appears to be GONE from the market entirely nowadays. A few years back, I was able to buy a huge bag of organic top soil in Lowe's for something like $3, and now I cannot find it anywhere. Do you think using non-organic top soil is acceptable? Could it be containing chemicals / toxic residue that can harm livestock? What are your thoughts on also adding some Osmocote Plus to the very bottom of the tank and mixing some bone meal into the soil? A youtube channel called Father Fish recommends employing both of those, as well. Finally, may sound silly, but I am completely overwhelmed with the pottery clay part. I wouldn't know how to deal with a block of it, and I don't know which one is natural, ect. Is it ok to make things simple by ordering this supposedly food grade powdered clay? Thank you so much in advance! https://www.amazon.com/Natural-Indi...3V02FEDaB1S9RZ4Zt729FQiiL49spJEDNwyJaSXKIpRcw
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top