By: Kelsie Fronheiser, Gene Edwards, Jenny Kraus, Justin Lange


These instructions will help you create your very own eco-column in your home or classroom. An eco-column is a self-sustaining ecosystem on a small scale, made of plastic soda bottles.

This eco-column has 3 chambers: the terrestrial chamber, the decomposition chamber, and the aquatic chamber. The terrestrial layer represents the land habitat including plants and insects (if desired). The decomposition chamber represents a leaf litter habitat, much like a compost pile. The aquatic chamber is a mini freshwater habitat for aquatic plants and even small fish.

All three of these chambers make a “mini-ecosystem” that you can observe at home or in a classroom setting. You can see the interactions between the chambers as you water the plants that grow in the terrestrial chamber and watch the water travel through the decomposition layer all the way to the aquatic habitat below. This project is perfect for those who want to learn about the environment and how it works, which is why it is a great project for students of all ages.

Time Required:

About 60 minutes

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Step 1: Materials & Tools

Required: Where to Obtain

  • Exacto knife
  • Hammer
  • One medium-sized nail: Hardware stores such as Home Depot or Lowes
  • Rubber band
  • Black Sharpie
  • Measuring tape
  • 3 clear 2 liter soda bottles and caps (avoid Canada Dry- labels are very hard to get off)
  • ~3 cups of aquarium gravel or small rocks: Pet store, creek beds
  • 5-6 cups of soil, organic or untreated: Garden stores or garden sections of popular superstores
  • Dead organic matter such as leaves, small sticks, dead bark
  • Small aquatic plant (hornwort, ludwigia, moneywort, cabomba, myrio, etc.): Pet stores
  • Seeds of small plants such as grass, radish, arugula, basil, etc. (these examples are fast-growing): Garden stores, supermarkets
  • Untreated tap water or distilled water: Leave tap water sitting out for one night before use.


  • Aquatic fauna: Betta fish (recommended, click here for more information), freshwater snails, crayfish, etc.: Pet stores, creeks, ponds
  • Terrestrial fauna: snails, worms, pill bugs, small insects (fruit flies, earwigs, beetles), millipedes, etc.: The woods


The Exacto knife contains a sharp blade. Always remember to cut away from yourself. It may be easier to cut the bottles while holding them horizontally. To avoid injury use caution while using the Exacto knife. Keep Exacto knife away from small children.

Children should be supervised if using the hammer and nail in order to avoid injury. Be sure to work on a hard, flat surface when using these items to avoid injury and damage to work surface.

Step 2: Cutting the Bottles

Tip: Label the bottles: Bottle 1, Bottle 2, Bottle 3

1. Use the measuring tape to measure 1 inch higher than the label on Bottle 1
Tip: Use the rubber band and the Sharpie to draw lines where you want to cut (see above images)

2. Use the Exacto knife to cut Bottle 1 where you just measured

3. Use the Exacto knife to cut Bottle 2 at the bottom of the label
Tip: Keep the bottle cap for Bottle 2

4. Use the Exacto Knife to cut Bottle 3 at the bottom of the label
Tip: Keep the bottle cap and the cut off bottom of Bottle 3

5. Peel labels off of all bottles

Step 3: Cutting the Bottles- Part 2

6. Use the hammer and nail to poke 5-6 holes in the bottom piece of Bottle 3 (see above image)

7. Use the hammer and nail to poke 5-6 holes in the cap of Bottle 2

8. Use the hammer and nail to poke 5-6 holes in the cap of Bottle 3

9. Use the Exacto knife to cut a 1/2 inch by 1/2 inch flap 1 inch from the top of Bottle 1 (see above images). This flap is what will allow you to feed your aquatic organisms.

Step 4: Bottle 3- Terrestrial Layer

1. With the cap on, add about 1 cup of small rocks

2. Fill the bottle approximately halfway with moist soil. If the soil is very dry, mix with a little water before putting it in the bottle.

3. Distribute seeds atop soil

4. Cover the seeds with a thin layer of soil, about 1/4"

Step 5: Bottle 2- Decomposition Layer

1. With the cap on, add about 1 cup of small rocks

2. Place 2 handfuls of moist soil in bottle

3. Fill bottle halfway with organic matter

Optional: place pill bugs, worms, or other small arthropods in this layer.

Step 6: Test

1. Put Bottle 3 on top of Bottle 2

2. Pour water into Bottle 3

  • If water comes out of Bottle cap 2 continue to next step
  • If no water comes out of Bottle cap 2 refer back to steps 7-8 of Cutting the Bottles- Part 2

Step 7: Bottle 1- Aqua Layer

1. Add about 1 cup of small rocks

2. Place the aquatic plant into the aquatic chamber so that the roots are covered with rocks

3. Add water into the aquatic chamber (Be sure not to fill the chamber above the feeding hole made in Step 9 of Cutting the Bottles- Part 2)

Optional: Add the Beta fish and/or other aquatic fauna

Step 8: Finishing Up

1. Stack the bottles as follows:

  • Bottle 1 on bottom, Bottle 2 on top on Bottle 1, Bottle 3 on top of Bottle 2, bottom piece of Bottle 3 on top of Bottle 3

Note: Don't be worried if your terrestrial chamber bottle sinks down into your decomposition chamber, this is normal and will not pose an issue.

2. Add water to the bottom piece of Bottle 3.

Note: If the cap of bottle 2 dips into the water in your aquatic chamber (like in the pictures above), remove water until there is about 1/2 inch or so between the cap and the water's surface. Failing to do say may prevent proper drainage.

For Classroom Instruction: You may want to complete “Cutting the Bottles” (steps 1-8) before class.

Caring for your Eco-coulmn: Add 1 cup of water to Eco-Column every 4 days.

Thanks so much for reading! We hope you enjoy your homemade eco-column! If you have any questions or suggestions feel free to leave us a comment!

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    23 Discussions


    3 years ago

    I am looking to work in a similar project but still thinking about relationships.

    What is the relationship between the aquatic chamber and the compost chamber if they are not in contact? I would need to feed the fish because does not have a source of nutrients so the system is not self sustainable.

    2 replies

    Reply 2 years ago

    The fish receive nutrients from the compost that exits from the straw into the water containing the fish. It is "self sustainable".


    Reply 9 months ago

    What straw? There is no straw listed in these instructions. I've seen use of nylon cords in other projects.


    4 years ago

    Wouldn't it make more sense to put worms and pill bugs in the decomposition chamber, as that is what they do for a living?

    2 replies

    Reply 4 years ago on Introduction

    Yes, it does make more sense as the animals will help with the decomposition process. I have changed the instructions to reflect your input :).


    Reply 1 year ago

    Okay, there is a problem here then. Since you changed the directions to put the worms, insects, etc. to the decomposition chamber instead, that is what we did. I understand that is what bugs do (break down the material), however, I thought it was strange that we were putting the insects in the middle section where there were no holes, etc. poked in for any air. But, we followed the directions anyway. Sure enough....all of the worms and crickets died within in a few days. Shouldn't there be some sort of air going into that middle decompositon layer if there are going to be live bugs in there?


    2 years ago

    where is step 9 for cutting the bottles?


    2 years ago

    Please answer by tomorrow. It's an emergency! (Not really, but I just need the answer) I have been searching everywhere, but it doesn't say. I would be glad if you'd helped. My question is "would it be okay to have one of the bottle to be different from the rest to construct this column"? Thanks! :)


    2 years ago

    i hope mines comes out this great


    3 years ago

    What are some things that students could measure if using this as a project based assignment? Water temperature, grass growth, decomposition? Looking for suggestions


    3 years ago

    Well put, well memed, all round a jolly fine projectarino m8


    4 years ago

    How often should one change/add to the decomposition chamber? I'd assume once the worms/micros decompose the material, it becomes regular soil. Or should this layer not be changed?

    1 reply

    Reply 4 years ago on Introduction

    Yes, you'll want to add to the decomposition chamber once most of the leaves have decomposed. We don't yet have an estimate on how long that takes because we haven't had to add anything to our decomposition layer yet.


    4 years ago on Introduction

    Interesting looking project! My big concern would be stability. Is it pretty steady once stacked or would a jostle of the table or accidental bump send all this toppling? Any suggestions for locking sections together into a solid form? Maybe some kind of slot/tab or nut/ bolt combo through the plastic?

    1 reply

    Reply 4 years ago on Introduction

    Tape is probably your best bet. Your project should be put where it cannot be jostled around.