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Comment by gravypod | Hacker News Reader

These sealed aquatic systems are really cool. How do you go about finding out how much of everything you need to put in them for long term survival?

Can the biological processes of these simple organisms be modeled as checmical equations and all you need to do is balance them out and solve for the mols of everything you need to pour in?

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> These sealed aquatic systems are really cool.

I find them more cruel, as you knowingly doom your pet world to die a few years later.

It could be worse: https://www.thedodo.com/live-animal-keychains-china-12256846...

https://www.thedodo.com/watch-holds-captive-ants-1057364913....

The keychain thing reminds me of this: https://medium.com/the-mission/a-visit-to-the-dead-tiger-war...

“…humans are monsters.”

“Yeah…” she replies. “We really are.”

That's why I haven't made one yet. I'd like to make one that contains a correctly proven amount of every nutrient and will, for a fact, stay alive for a long long time.

Ironically, we're doing it to ourselves at the global scale, to ourselves and tons of other organisms. It's only when the scale is so small that we can hold it in our hands, that we start to empathize.

Guessing it's a bunch of trial and error right now - these systems are pretty hard to predict in general and I'm not aware of a whole lot of research into closed ecological systems. Which is a shame really.

A self-sustaining system like we'd want should come to its own dynamic equilibrium, given a decent enough starting state, which does make the trial and error slightly more feasible, and of course they have to have some idea of the inputs and outputs of the various organisms.

There is some research on these ecosystems [1], and there dynamics [2,3]. The ecosystem is made up of a photosynthetic algae as a producer, a protozoa as a consumer, and a bacteria as a decomposer, and can be stable for over 1,000 days.

[1] http://ir.obihiro.ac.jp/dspace/bitstream/10322/221/1/Prot.Vo...

[2] http://www.cell.com/cell/pdfExtended/S0092-8674(12)00515-6

[3] http://journals.aps.org/prx/abstract/10.1103/PhysRevX.5.0410...

Stable for 1000 days is not the same thing as 'will remain clean for 1000 days'. Have this phones a undisclosed problem with overheating that would suggest to add water as heat buffer?

> I'm not aware of a whole lot of research into closed ecological systems

I'm sure NASA and SpaceX have to be doing something like this.

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