A closed aquatic ecosystem is similar to an aquarium, but is completely isolated from the rest of the world; it must therefore contain everything that allows the life of animals and plants. Most of the species that can be included in this system are not very large or colorful; therefore, if you want an ecosystem full of fish of various types and aquatic plants, you should opt for a traditional aquarium. However, read on if you're interested in building a maintenance-free aquatic world that can last for months or even years!
Steps
Part 1 of 3: Getting the Correct Materials, Plants and Animals
Step 1. Decide which container to use to enclose it
The more isolated the aquatic ecosystem is from the outside world, the more difficult it is to build a self-sufficient one.
- The hermetically sealed systems are completely isolated, plants and animals must be few and very small in order to survive.
- Closed systems allow an exchange of gas and air (for example by placing a sponge over the opening). The gas exchange allows to regulate the pH of the water, to eliminate nitrogen and to expel carbon dioxide; these systems are the simplest to maintain.
- The semi-closed ones need some maintenance. Eventually, all closed ecosystems collapse; you can try to extend its life by changing 50% of the water every month, in order to eliminate waste and add nutrients. If yours is dying, change the water more frequently.
Step 2. Decide if you want a marine or freshwater ecosystem
The freshwater ones are easier to make and maintain, while the marine ones are less stable, but allow the observation of more interesting creatures, such as anemones and starfish.
Step 3. Purchase a glass or clear plastic jar to hold the ecosystem
Those for jam, biscuits, two-liter plastic bottles or 12-15-liter demijohns are perfect, although beginners have less difficulty maintaining smaller ecosystems.
If you want to make a sealed system, choose a container with an airtight cap; if you have opted for the closed one, consider putting a cheesecloth or sponge over the opening
Step 4. Find a substrate for the plants to grow
You can buy it from pet stores or collect it from the bottom of a pond (which has the advantage of already containing several small creatures). Consider adding a layer of sand on top of the substrate or mud to get a clearer ecosystem and keep the water clear.
Step 5. Purchase some aquatic gravel or get it from a pond
This layer is the surface that allows the microbial colony to grow and acts as a filter by trapping the particulate that falls down by gravity.
Step 6. Use filtered water, pond water or aquarium water
The last two are to be preferred, because they already contain the bacteria necessary for the life of the ecosystem. If you are using filtered water, you will need to let it sit for 24-72 hours so that the chlorine can dissipate.
Step 7. Choose plants or algae
These provide nourishment and oxygen to the ecosystem; they must be robust and fast developing. You can get them from a pond or buy them. Some plants you can consider are:
- Common Ceratofillo (freshwater): it is very robust and needs moderate light;
- Elodea (fresh water): it is resistant and needs soft light;
- Fontinalis antipyretica (fresh water): it is less resistant and prefers low temperatures;
- Utricularia (fresh water): delicate;
- Caulerpa taxifolia (salt water): it is so resistant as to become a pest;
- Simple algae (salt water): they need high levels of calcium;
- Valonia ventricosa (salt water): it is very robust and can become a pest.
Step 8. Choose the animals
They eat algae and other waste while keeping the ecosystem clean; they also produce carbon dioxide, which allows plants to survive. Start with one or two large animals or 10-20 hyalella. Attention: fish are not suitable for a closed ecosystem; if you decide to insert them anyway, they will die. Here are the animals best suited to a closed aquatic ecosystem:
- Neocaridina davidi (fresh water);
- Melanoides tubercolata (fresh water);
- Hyalella (fresh or salt water according to the species);
- Copepods (fresh or salt water depending on the species);
- Asterina starfish (salt water);
- Glass anemone (salt water).
Part 2 of 3: Building the Aquatic Ecosystem
Step 1. Add substrate (potting soil) to the bottom of the container
If you are using a bowl with a narrow opening, consider using a funnel to avoid mess.
Step 2. Plant the aquatic plants
Once water is added they tend to float, so you should cover them with some sand and gravel to allow them to take root.
Step 3. Lay out a layer of sand and then a layer of gravel
Cover any soil that remains exposed, but be careful not to crush the plants. Plants, substrate, sand and gravel should collectively occupy 10-25% of the container capacity.
Step 4. Pour the water
Remember that if you are using the filtered one, you need to be sure it has rested for 24-72 hours so that the chlorine has evaporated. The water should occupy 50-75% of the volume of the container. Leave 10-25% free space for air.
Step 5. Add the animals
But first, allow them to adjust to the temperature by letting the bag float on the surface of the water for a few hours. Remember to start with no more than a couple of shrimps or snails or with 10-20 specimens of hyalella. The presence of too many animals kills the ecosystem.
Step 6. Seal the container
If you've opted for an airtight ecosystem, you can use a screw cap or cork, although cling film and a rubber band are sufficient if that's all you have. For closed systems (which allow air exchange), you can use a cheesecloth or a sponge plug.
Step 7. Place the ecosystem in filtered sunlight
It should be near a window that does not receive direct sunlight for many hours, otherwise the sudden changes in temperature will kill the snails and shrimp. Shrimps, copepods and snails prefer a temperature between 20 and 28 ° C, the container should be cool to the touch, but not cold.
Part 3 of 3: Maintaining the Aquatic Ecosystem
Step 1. Observe the ecosystem carefully during the first few weeks to make sure you have placed it in the right place
An excess or scarcity of sunlight can kill it.
- If the plants seem to be in poor health, try exposing them more to the sun.
- If the water is getting cloudy or dark, make the ecosystem get more sunlight.
- If you have algae or the shrimp dies on hot days, put the container away.
- Remember that you have to move the ecosystem according to seasonal variations.
Step 2. Adjust the number of animals and plants as needed after the first few weeks
It's important to keep the ecosystem healthy, as you probably won't be able to strike the right balance right away.
- Add more snails or shrimp if you notice an algae bloom. It is important that these plants are kept in check, otherwise they cover the walls of the container blocking sunlight and killing other creatures.
- If the water becomes cloudy, it could be a sign that there are too many shrimps or snails. Try adding more plants.
- If the animals are dying, add more plant material.
Step 3. Know when the ecosystem died
There is no point in keeping a system that has run out, especially if it starts to smell bad. These are the signs that you need to empty the container and start over:
- Bad or sulfur smell;
- Filaments of whitish bacteria;
- There are few living animals left or all of them have died;
- Most of the plants died.
