Hi there, it's nice to notice a bit of life on this group. (like an
abandoned biojar, it just might surprise you...)

I'm a reporter who wrote in here about a month or two ago looking for
people to interview about this subject. Thanks to the people I talked
to on the phone and/or by email.

I have an article coming out in a national magazine next year that
will give a detailed recipe for a homemade biojar that should be
considerably more successful -- in the sense of keeping macroscopic
animals alive -- than just throwing some pond water in a jar. My
sources were academics and some people who have contracted with NASA
for small aquariums.

While I can't give that whole recipe, I can tell you a great source of
basic advice, and repeat some of the guidelines I found there.

The source of basic advice is a book called ECOLOGICAL MICROCOSMS by
Beyer and Odum. It should be in a lot of college libraries. It has
instructions for creating classroom microcosms.

Assuming your goal is to keep some sort of charismatic animal alive,
Beyer & Odum's guidelines basically point you towards trying to
maximize the amount of oxygen available for that animal. That means
you want to encourage photosynthesis and discourage oxygen
consumption, especially by microscopic algae. So they'd say:

1) keep the ratio of plant to animal biomass very high, 20:1 or
higher. That means your charismatic animal has got to be small --
probably an invertebrate instead of a fish. And it should be one that
can eat algae and also just any old debris.

2) use vascular plants as well as algae for photosynthesis.

3) use abundant light but not full sun. regular room light or
aquarium light is not enough.

4) the initial water mix should be IMPOVERISHED in terms of nitrates
and phosphates, because these encourage algae which tend to hog
oxygen. don't just chuck pond water in a jar -- it will be way too
rich most of the time.

5) oh, and if you use tap water, dechlorinate it!!

Hope that helps,

Martin John Brown
http://martinjohnbrown.net