Things You'll Need
Tarp or plastic sheet, roll or tablecloth
Muriate of potash
Aquarium soil substrate differs from typical gravel aquarium substrate because it contains nutrients to promote aquatic plant growth. Aquarists who want a lush green landscape in their tanks need a substrate that can support plant life. However, many problems can occur when using regular garden soil and fertilizers, such as algae overgrowth. Mixing a soil that is rich with clay and low in algae-promoting fertilizers will keep your tank clean while promoting the growth of your plants.
Pour the topsoil into a container. Fill the container with water until the water level reaches 1 to 2 inches above the soil level. Break up or stir the soil so it becomes thoroughly saturated.
Allow the soil to soak in the water for 2 days. Drain the water, then repeat Step 1 by adding more clean water after draining. Let the soil soak for another two days, then drain.
Empty the wet soil onto a clean tarp, plastic sheet, plastic tablecloth, plastic painter's drop cloth or a very large, wide container, then spread the soil into a thin layer. Allow the soil to air dry completely. Speed the drying time by placing the soil outdoors on a sunny and dry spring or summer day.
Repeat Steps 1 to 3 two more times to neutralize the fertilizers in the soil that will contribute to green, murky water and algae.
Sift the dry soil through a strainer to remove debris, and return the soil to the original container.
Add 1 part pottery clay to 10 parts of soil. Pour warm water into the container and mix the clay and soil together until a cake batter-like mud has formed.
Sprinkle a small dusting of muriate of potash, a fertilizer, on the bottom of the empty aquarium. Pour the muddy soil/clay mix into the bottom of the aquarium.
Cover the mud with a layer of gravel of your choice. Some common choices include pea gravel, river stone and aquarium sand.
Refill the aquarium with water, add your plants and replace your fish.