Building an ecosystem terrarium entails placing a variety of living and nonliving things into a partially closed environment and letting them interact naturally. The communities within the terrarium are classified as the ecosystem. Most kept terrariums begin with a source of water and build a habitat of plants, fish or small animals around the water. For the ecosystem terrarium to remain viable, plant and animal species must be compatible with each other. Compatible species are found coexisting naturally outdoors.
Find a container. A small fish tank is the most commonly used container to build an ecosystem terrarium, but any glass container with a tight-fitting lid will work. Plastic containers can be used, but glass will allow for the moisture to be recycled more easily within the terrarium. Wash the container with eco-friendly soap and water to ensure that there is no residue or growth inside it.
Lay 1 inch of gravel on the bottom of the container. Gravel can be purchased at a pet supply store or can be collected from the outdoors. If the gravel is collected from outside, wash it with eco-friendly soap and water before putting it inside the container.
Add a light layer of activated charcoal on top of the gravel to help the terrarium drain and recycle water effectively. Activated charcoal can be purchased in the aquarium section of a pet supply store.
Add a layer of soil on top of the activated charcoal. The soil is best harvested from the natural ecosystem that you are trying to recreate. If you are creating an ecosystem based on the region in where you live, the soil can be collected from a local source. If your terrarium will showcase non-native plant species, buy appropriate soil from a pet supply store.
Add plant and animals to the terrarium. Plants should be spaced at least 3 inches apart in the terrarium and planted deep within the soil and charcoal layer. Plants can be bought or harvested from a local source. Place small animals that feed on the particular plant species into the terrarium. Some common animals include terrestrial snails and insects. As the animals eat the plants, their droppings will provide fertiliser for the plants to grow. Rocks and other natural materials can be added as well.
Add water to the terrarium. Pour water into the terrarium until a 1/2 inch is visible on the bottom of the container. The presence of the gravel and activated charcoal create a type of groundwater source, or aquifer, which will supply the plants with needed moisture and provide proper drainage to keep the terrarium from becoming waterlogged. If you are housing larger insects or animals inside the terrarium, you may add a small water source, like in the bottom of a small cut-off paper cup, for example, to provide an extra resource for drinking.
Maintain the ecosystem terrarium as needed. Many terrariums do not need to be attended more than once a month. At this time, they should be watered and any dead plant or animal material should be removed.