Can You Use Normal Soil in an Aquarium?

One of the best ways to have lush underwater plant life in your aquarium is to use a substrate. While there are many, soil can be one of the best to promote this plant life. It is simple to purchase soils that are ideal for use straight away in an aquarium such as Amazonia Soil, or you can purchase other things like natural planted substrates.

Yet, there are aquarium owners who don’t wish to spend on something they can see lots of outside in their gardens. These soils are expensive so that it can leave a curious tank owner wondering:

Can you use normal soil in an aquarium? A good substrate can make a huge difference to the results you get with your live plants in your aquarium. Using soil straight from the garden isn’t a good recommendation because it isn’t organic, and non-organic soil can kill your fish. However, with the right steps, you can create your aquarium soil substrate.

We will show all you need to know about using soil in your aquarium, and the steps to make your own should the urge arise.

Using Regular Soil in Your Aquarium

There is a large trend for tank owners to have live plants in their aquarium because it does make a significant difference to an aquascape instead of using plastic plants. While it is possible to use another substrate than soil, the soil does deliver certain nutrients other substrates don’t offer.

It doesn’t matter if you want to use regular soil as a cost-saving exercise or not; there are easy steps to follow when using garden soil for your tank.

The one thing to note is that you can use organic potting soil with less effort than your garden soil. You will still need to remove foreign items from it, but it won’t contain any of the harmful additives, fertilizers, and it will be chemical-free.

Method One – Using Garden Soil

  1. Gather your soil from your garden in a bucket.
  2. Sift your soil to remove any twigs, stones, and insects (Make sure you have enough to cover the tank bottom to a depth of around 2-inches).
  3. Take the sifted soil and sprinkle it on baking sheets.
  4. Bake at 200°F for 20-minutes. (This helps sterilize the soil. It will kill any seeds, unseen residents or microorganisms that may be harmful to your fish).

These are the only steps to prepare soil from your garden. If you purchase potting soil, the steps are a little different and don’t require the use of the oven (you can follow this step if you wish).

Method Two – Using Organic Potting Soil and Clay

When you purchase your potting soil, make sure it is organic and chemical-free. Again, you need enough that will cover your tank base by around 2-inches.

The steps for preparation take a little longer than the previous method, so allow a couple of days before you decide to use your new soil substrate. The introduction of clay adds a good source of iron. Doing this helps your plants to develop healthy and strong structures.

Items you need

  • Large buckets
  • Mesh for filtering
  • Stick for mixing
  • Large sheet for drying
  • Sand or gravel for your cap (sealing substrate)
  • Modeling clay – unfired (some fish owners use clay kitty litter)

Steps for Soil Preparation

  1. Sift your soil into one of your large buckets to remove unwanted bits
  2. Fill the bucket with water until it covers the soil by around two inches
  3. Mix the soil, so it is all saturated
  4. Soak for a day or up to two days
  5. Drain through your filter into your second bucket and repeat the above steps
  6. After another day or two, drain your soil liquid
  7. Spread thinly onto your sheet and air dry (sunnier the better or you can use the oven method to speed up drying)

Aquascaping with Your Soil Substrate

If this is the first time, this can be the hardest step when using soil as your substrate. You will probably get quite dirty in this step. These steps take into account if you already have fish in your tank, and are adding substrate to add live plants.

If you follow these steps, you can add your fish back to your tank once you have done your aquascaping. Your soil will need to be prepared ready for use at this stage.

  1. Get a large container for your fish and fill with some of your tank water
  2. Carefully transfer your fish to this tank
  3. Add your tank heater, air stone, and filter to the temporary fish tank (by doing this, you will be saving plenty of beneficial bacteria, so there will be no tank recycling)
  4. Drain your original fish tank and remove all the gravel and plastic castles and plants you have
  5. Dry your tank as much as you can, adding your soil substrate to a wet tank makes it watery, and your cap will sink
  6. Some tank owners will run their cap around the tank edges to hide the soil. It is an optional choice based on preference. Some aquarium owners also like to work with moist soil; you can lightly soak and drain before use as it can help with aquascaping.
  7. Add your soil and slope it upward to the rear of your aquarium if you want the sculptured look in your tank. Take note: if the soil is too thick, you can find toxins are created, and if too thin, it won’t be thick enough for roots to take hold.
  8. As you add your soil, break up your clay into small chunks and scatter across the bottom of your tank.
  9. Add your cap to the same thickness as your soil. If you add two inches of soil, then add two inches of your cap in that area. Doing this will make sure your soil remains in a position where it should be.

Planting into Your Fish Tank

There is a divide on how tank owners go about this step. Some add plants immediately, while others fill and drain their tanks several times before planting. Through experience, there doesn’t appear to be much difference which way you go.

You can decide as you begin filling your tank, so here are the steps to take for planting.

  1. Add water to no more than four inches above your cap substrate
  2. If the water is clear, you can continue, if not, drain and re-fill until it is clear
  3. Once the cap is holding the soil and water is clear, drain, and do your planting. At this point, you may have an issue with algae, as it will love the added soil nutrients you have added. The solution to this is to add sufficient numbers of plants that they will soak up all the nutrients for themselves, so there won’t be sufficient for the algae to bloom. Duckweed, java moss, anacharis are great for this.
  4. The filling can be the hardest step, as you don’t want to disturb your substrate, because all the hard work will be undone. Start filling with dechlorinated water that is heated to around 78 degrees Fahrenheit. It can be easier to pour onto a plate or dish to break the fall of the water. 
  5. You need to cycle the tank for a while, as the soil will be releasing ammonia and other things you don’t want. If you already have your fish and an established colony of bacteria, you can begin adding your fish using drip acclimatization.

After Planting in Your DIY Aquarium Soil

Once you have your tank planted, and your fish reintroduced to their new lush surroundings, there are a couple of things to do and be wary of.

For the first two or three weeks, you need to carry out ten to fifteen percent water changes daily. Doing so will maintain excess nutrient levels while your new plants adjust to their environment.

The second thing is you may see plants start to look unhealthy and melt or wilt. It is a normal condition. Even if they appear dead, plants go through this phase as they get used to their surroundings. They will revive themselves and grow stronger as a result.

What you do need to look for is signs of new growth. If there are signs, then you have nothing to worry about, aside from the need to be patient. Plants can take care of themselves, and before you know it, you will have a beautiful lush green aquascape that you can be proud of, and your fish will love.

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Adam Edwards
Hi, my name is Adam and I'm an aquarium enthusiast! I didn't discover the joys of being an 'aquarium fanatic' (as some of my friends call me!) until I was in my 20's. When I first started out I found it difficult to find all the information I needed so I started this website to compile all the useful information I can think of. Enjoy!