# What is a closed system?



## Jeanine (Apr 4, 2009)

While buying plants at the LPS, a lady mentioned that she had a closed system (I believe that's what she called it). I overheard her say that it has a glass cover and she just topped up water once in a while. So now I'm wondering just what one is and what it involves to set it up. Is it the same as a el natural? What would one keep in one?


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## Alex123 (Jul 3, 2008)

Wiki says:
"state of being isolated from its surrounding environment"

No system is closed system, but on subject of aquarium, when you go through the nitrogen cycle, all aquarium in some sense are closed system. You feed the fish, the plants/bacterias breakup the fish pooh into nutrients for plants/other bacterias and a cycle is formed hence a closed system. She might mean that she does less things to keep her aquarium running. Maybe she doesn't have a heater or water change, or no filters/pumps, or no light or no food. But I doubt the latter two are the case. You have to ask her what she means by closed system.


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## Cliff Mayes (Jan 29, 2007)

Please report back. I too would like to know.


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## mudboots (Jun 24, 2009)

The first thing I think of is those bio-ball whatevers, maybe BioOrbs? It's pretty much sealed off once you stick your little dwarf ACF (or whatever you decide on) in there with enough other junk to keep him alive and add tiny amounts of water if you ever notice evap through a little hole.

But there is also a sump system, which is pretty elaborate, called a closed system. They are basically an aquarium beneath your aquarium (has lights, plants, filter media, substrate, the whole 9 yards depending on your individual system and preference), and I've heard of some folks' sumps being more complex than their actual tanks.

Other than that I can only think of the emmersed set-ups that are on an unmanaged routine, like the one I keep sealed up in my son's room. It got started off with a little fertility, water, plants, et cetera during the scaping, and from then on the only time I get in there is to wipe down the glass to take a pic or two to post in the journals forum.

Like Cliff said, keep us posted Jeanine.


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## addicted2reefin (Oct 2, 2009)

closed system in definition is a system that recieves nothing from an outside source, which in definition, the only closed system would be the universe. 

u remember those little eco-orbs or whatever there called they used to sell at the mall back in 2000. they were sealed completely, and had a frog or gubby and a plant or two. all u had to do is give it some light. thats bassically as "closed" as it gets.


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## brighty K (Oct 1, 2008)

I think these are interesting too.

The "ecospheres" I have seen (with marine shrimp, algae, and what not in a sealed glass container) began as a NASA project. In 1968 Dr. Clair Folsome (University of Hawaii) sealed some water, algae, and microbes in a bottle and found that, even sealed, the microbes and algae kept on living. He experimented with different algae and microbes, some of them living for more than twenty years!

I ran into this in a book about NASA's Biosphere 2 project.

The small "ecospheres" are still available, shrimp and all, as are larger installations, like this one:


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## Philosophos (Mar 1, 2009)

No tech systems are where we started, and where we touch back on at times. Internally balanced aquariums are something that have always had a place in the hobby. The concept of having a beautiful tank that requires little to no maintenance is the epitome of utility. I see a place for using these sort of setups to test ourselves and our knowledge of aquariums as a whole.


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## brenmuk (Oct 7, 2008)

These are, I think the ecospheres people are referring to:-

http://www.aquaessentials.co.uk/index.php?main_page=index&cPath=298_183_270

They are closed systems in that they are completely isolated from the outside environment....except from light and heat and other forms of EM radiaton and vibrations .......


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## Noto (Oct 26, 2009)

Those ecospheres feature _Halocaridina rubra_, an exceptionally tough tidepool crustacean that can survive for years before finally succumbing to starvation. They are not self-sustaining ecosystems, just very slowly failing ecosystems.


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## Philosophos (Mar 1, 2009)

Noto said:


> Those ecospheres feature _Halocaridina rubra_, an exceptionally tough tidepool crustacean that can survive for years before finally succumbing to starvation. They are not self-sustaining ecosystems, just very slowly failing ecosystems.


Entropy would dictate that the entirety of existence is a failing closed system; it's not possible to make a truly self-sustaining ecosystem. I guess its really a matter of semantics and how long something can carry on before we arbitrarily consider it self-sustaining. Life for a certain length of time? Number of generations? Speciation?


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## Jeanine (Apr 4, 2009)

Wow. This is really interesting. I live in a small one pet store town and I've never heard of ecospheres before. They sound pretty neat. 

I'm pretty sure that the lady had a tank with plants and a piece of glass over it and she just let it do it's thing adding water once in a while. Next time I go in, I'll have to ask her what she has going on. 

I have a 1 gallon hexagon experiment (not sure if it could be called a closed system or not) set up with aquasoil, capped with local river sand, a moss ball, a couple plant clippings from the lake, and a few snips of plants from my aquarium, (lugwigia 'repens', rotala rotundifolia, a small anubias,) and a small rock. Cyclops, some small snails, and some sort of very tiny worm (barely visible on glass) inhabit the tank. It's covered over with a piece of glass. It's been set up for over 7 months (a betta lived in it for the first month before it died I've been to scared to try another fish) with no water changes or top up for about 6 months. The water evaporates to the glass top and drips back in.
The leaves on the lake plants have turned see-thru, but i haven't removed them as I'm not sure if this is the time of year when lake plants die back in the winter. Plant growth is very slow with the other plants. The water turned green for a while in the summer with the bright sunlight but has cleared up now. The moss ball floats up and down, depending on the days sun. And I do see bubbles on some of the plants occasionally. Some sort of grass has sprouted and been slowly growing. I don't remember planting it, but maybe I did (I have some eleocharis parvala in my other tanks). Anyways, it's been interesting watching it just happen on it's own. I do see some debris on the bottom. I've been thinking maybe I should clean up the dead leaves, but maybe I'll just watch and see what happens awhile longer.

I've really enjoyed reading about peoples options and knowledge on this subject.


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## Cliff Mayes (Jan 29, 2007)

Ecospheres may be the first perpetual motion machine!

Does PHD really stand for piled higher and deeper?

The minute I am shown a tank with any kind of fish that is self suststaining I am in, I think.

Please, please, please Jennine let us know what she means!


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## Jeanine (Apr 4, 2009)

I was in the store talking to the lady today. I asked her what she meant by Closed System. She said that what she had was an aquarium that she set up with gravel, plants, fish and snails and then covered it in glass. She then did what she said was the hardest thing which is to leave it alone. No taking out plants, or fish that died or opening it up to do water changes. Just letting the tank do its thing. She left the tank for a year and a half without doing anything to it, before she took it apart. 

Has anyone else done this?


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## bartoli (May 8, 2006)

So, she did not feed her fish?


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## Jeanine (Apr 4, 2009)

I believe she used live bearers like guppies, so they could eat their offspring.


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## Diana K (Dec 20, 2007)

Very small fish would eat microorganisms, too. 

I think with a large enough tank something like that might be possible, but the components would have to be carefully selected so that none outgrew the set up to the point of overwhelming all the other things.


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## bartoli (May 8, 2006)

I wonder whether there is anything to do with the healthy impact of calorie restriction as in human and mice.


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