Aquarium Dopers: A closed ecosystem!

I’ve been playing around with the idea of having a closed ecosystem, mostly as an engineering project. Much like my attempts at bonsai rearing, my ambitions are rather humble, a system with a couple of plant species and one or two invertebrates is more than enough.

My goal is to create a small hermetically sealed chamber (e.g a jar) that will maintain one or two species living in symbiosis. Do any dopers out there have suggestions for what species to use, and in what proportions?

Such a thing already exists and has been marketed for years: However, its considered by many people that it is a least a little dubious to say that this is a perfect, self-regulating, closed system. As well as some outright crackpots who claim it is a slowly dying ecosystem torturing the shrimp.

One of the most important things with this particular … um, toy, I guess, that people seem to have forgotten is that it must be kept at fairly normal temperatures, and tightly restricted light levels, so the alga only grows slowly. Left in a bright sunny window, the alga blooms, consumes all nutrients and dies. 'Course if that happens, you just ship it back to manufacturer, and they restock the sphere for a fee. Which kinda defeats the whole purpose of nurturing a mini-ecosystem, but YMMV.

Now you plan is not to use water, but a terrestrial version. That is going to be tougher. You want nutrients to cycle, form animal waste and decomposing bodies, with no realistic method for producing erosion, rain and other weather. That is going to be tricky.

This is available commercially.

Whatever you do, don’t put Pauly Shore in it.

No, please put Pauly Shore in it.

Are they crackpots for believing it’s a slowly dying ecosystem, or that it’s torture for the shrimp? Putting aside the “torture” part, it does seem logical that the ecosystem would be dying. I’d be interested to know if it’s even practically possible for an amateur to make such an ecosystem that can last indefinitely.

I assumed it was with water. He didn’t specify but the thread title does mention aquariums.

I did find this thread on the subject, although it doesn’t seem to have much new information.

I also found this blog which might be interesting.

The Wikipedia page points to a classroom demonstration about building an ecosystem yourself. And has an offsite link as well. Maybe a high school or grammar school could build a shrimp and algal terrarium that lasts the entire school year or longer.

Twenty years ago, when these Ecospheres ™ appeared in the Edmund Scientific catalog, you could also purchase a light meter to measure the light dosage. When you hit the quota for the day, you were supposed to move it into the dark. The advert blurb in those days said that with proper light maintenance, the ecosphere would maintain for years. And that some evidence of life cycle for the shrimp. That means, they grow bigger, they lay eggs, smaller shrimp appear and grow, the ones that die soon disappear rather than accumulating. I suppose that counts as winning. Or is it lasting for years a minor win? But if you can have it recharged at any time, well, what;s the point?

The people I call crackpots are referenced in the Wikipedia article. They used to edit the article, and they sell this species of shrimp. They say there is no evidence of life cycle, the shrimp just starve, and become smaller, lose their color as they moult into a new shell, and aren’t young. So this ecosphere is a cruel invertebrate torture device. Like I said, I can’t prove that it works, so I can’t say they’re wrong. Just a little knee-jerking on my part for the invertebrate animal rights crowd. Not for the dubious science.

My brother made one in a large jar which lasted many years, though not in any sort of equilibrium. It would go through cycles where algie would grow and little swimming things would live, then they would all (apparently) die off or grow dormant for a while, to reappear again some time later.