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Is it possible to create a completely closed environment? If I put the correct mix of invertibrates, plants, and fish can I set up a mini-ecosystem that doesn't require any interference?

If they cant do it with simple organisms like blind shrimp and elodea, it probably can't be done.

Definately not in a small tank... but possibly in a tank that's several thousand gallons or larger...

You'd have to put in a LOT of different organisms for it to work though, including predators (to keep other organism's populations down), etc, etc... would be rather complicated

i had a 3 foot aquarium, half full, planted with papyrus and elodea, with a trio of platties in it. it was outdoors and had a lot of insect larvae in it. i never fed the fish, and some of their progeny survived their infanticide - but this was hardly a closed environment - without access to the outdoor environment, the insects could never have established themselves. a truly enclosed environment is, in essence, a vaccuum...and you know how nature feels about those...

If you me closed as sealed completly it would be impossible as the water would get slowly poluted the plants would start to die end of story.

If you mean closed but space for air to get in it the water level would drop through evaporation again impossible.

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Keith

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My guess would be no. Most organisms aren't really cut out to live in closed environments anyway. Most fish come from lakes, rivers, and oceans that are most certainly not closed off from the outside surroundings. Even Devil's Hole Pupfish, the entire species living as they do in a single hole in the desert, are not in a closed environment; water pumping had to be banned nearby as apparently it drew from water from the Devil's Hole, which basically endangered the entire species' well-being. Self-sufficient closed environments are probably rare, if not completely nonexistant, in nature.

Of course, keith hit the nail that I didn't even see. Keeping up with evaporation is technically interference, and sealing it off to prevent evaporation isn't going to be cool for the oxygen-consuming inhabitants.:%)

Last edited by metagon at 22-Jan-2006 12:13

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The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.

I beg to differ!

I have said this before, with the result of being called a liar but with a fools persistence I will do it again.

When I was much younger (about twelve or so) I accompanied my uncle to a fishkeeping friend of his. I especially noticed a small plastic tank (say 30 liters) with the lid welded stuck. All way round the inside was covered with algae and from the top you could just see a green plant mass. This was an experiment he was doing, the tank had been planted heavily and stocked with some guppies and another livebearer, I don't remember which. His theory was that the plants and algae would transform carbon dioxide and wastes from the fishes into oxygen and tissues that would be used and eaten by the fish with occasional treats of new born fry.

I have no idea how long this experiment was carried out but a few years later I remembered it and asked my uncle what ever happened with it. He then said that his friend had opened the tank after his previously decided amount of time and that there were fish alive inside.

By the way this uncle was the person responsible for my interest in the hobby and unfortunately he is no longer among us or I could have asked him for more details. Of course I won't take poison on the fact that he was telling me the truth but why wouldn't he.

And if we just elaborate a little on the thought...
What is essential to sustain life?
For plant life: Light, carbon dioxide, oxygen, macros and micros.
For fish: Water, oxygen and food.
Herbivores have the food bit and oxygen bit taken care of with enough plants and algae and once eaten stuff come out the other end. Here we have the whole nitrogen cycle and all other waste transforming cycles making everything accessible for the plants again. Both macros and micros will keep getting available again and again.

The only limiting factor I can see here is light. As long as you can get some light in, and some will penetrate even the most algae infested tank walls, and stock a small amount of herbivores there ought to develop a state of equilibrium. After all, except for light, our whole planet is practically a closed environment.

Everyone is welcome to explain to me why this can't work but please no stupid one liners without you elaborating on it.

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So here I am once more...

It can be done! I do not know if it could be done with larger fish because when they become old and die the waste they create might be too much for the "ecosystem" to take unless you had say a few small fish in a large tank. I saw this around Christmas and thought it as jsut an absolutely nifty idea. I would love to ahve one for myself!

http://www.target.com/gp/detail.html/sr=1-7/qid=1138048645/ref=sr_1_7/601-2457871-7042512?%5Fencoding=UTF8&asin=B0000AIXPF

I of course do not know all the specifics but I do know that it is possible!

Also Here is a site for these eco-spheres

http://www.eco-sphere.com/home.htm

Christina

Last edited by dvmchrissy at 23-Jan-2006 15:01

Taken from the website:

"EcoSpheres have an average life expectancy of two years."

It can't be done. The shrimp, because they are kept in unfavorable conditions and cannot breed, eventually die and pollute the water, and everything else falls apart from there.

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I'm not your neighbor, you Bakersfield trash.

Here is the question again
Is it possible to create a completely closed environment?

Note one very important point is missing that is "Time". Saying that it would be impossible to carry the experiment out under controlled conditions

Yes it would work for a short period of time (how long depends on too many factors) Again define "Short period of time".

Here is another important factor. "Never assume anything". No time was given but if it was to be an extended "again define extended time" eventually every thing would die possibly the fish first then slowly the plants. This intern would cause massive pollution in the enclosed area and it would not support any form of aquarium life except in a form of bacteria.

The factor here is "Time" as it was not stipulated no actual correct answer can be given.

A very good question it creates a thought process which is often missing on many threads.

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Keith

Near enough is not good enough, therefore good enough is not near enough, and only your best will do.
I VOTE DO YOU if not WHY NOT?
VOTE NOW VOTE NOW

the eco sphere is probably as close as you are going to come. Frankly the only closed system I know that really works in this capacity is this planet. The ecospheres are realativly simple, but as it says the life expectancy is only two years. Im sure they are produced in a relativly sterile environment so they control exactly what goes in. You will have trouble doing that and something will disrupt your system. Also because aquatic ecosystems rely on interaction with both the air and soil and require nutrients provided by both. You could try, but I think on a small scale you will be fighting a loosing battle against thermodynamics.

Edit:: Robbamp is correct though on the point that your system will reach equlibrium. Though the equlibrium very well might be one which contains no life at all. ALso, of course, light is your biggest necsity. a dark system would find equlibrium very quickly.


Chaos

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