Vic Smith wrote in
:

Wow. Were the fish still reproducing after 15 years?
That's amazing. Never heard anything like that.
Seems like it would be commercialized.
Do away with the hundreds of bucks I spent on filters, aerators, etc
- bigger tanks of course.
How much water did the tubes contain?
Why no algae growth on the glass? I used plecostomuses to keep the
glass clear. The plec in my 55 gallon was about 16" when we moved.
Gave him to the pet store. Drew quite a crowd when I brought it in.



Yes, the reproduced right up to the end. So did the plants! It was a
self-contained, solar powered ecosystem. You can do it with a bottle,
but it's not as impressive, of course.

I don't think commercialization would work. You MUST provide LIGHT or
it dies, just like the Earth. You can't just turn it on and off taking
it out of a box so it wouldn't sell. The tube is about 7" in diameter,
10" high, something like that. As it was a closed, sealed environment,
no outside spores, like algae, can get inside. The balance of CO2 for
the plant to eat and O2 for the fish to breathe keeps the equilibrium.
Your algae come in the water and in the air, just like a swimming pool.
The air is full of spores. You were blowing spores into the water to
add oxygen to it. All the O2 in the tube came from the weeds.

I may have misspoke about sunlight. You couldn't sit it in the sunlight
or it would overheat, not good. There was no thermometer in it,
wouldn't fit through the evacuation tube, so your temp tester was
feeling the glass. Guppies are very hardy and heavy breeders so there's
a surplus. Dead, overload fish are simply consumed by the other
guppies. Any that rot and go to the bottom of the tube were consumed by
the plant. The combo of dead plant and dead fish made its own layer of
"earth" at the bottom of the ecosystem. The plant dutifully kept
consuming it with root systems....recycling the biomass. The only input
was light, for photosynthesis. O2 and CO2 couldn't escape the glass
envelope.

In operation in the transmitter, these tubes run blood red graphite
plates bombarded 24/7 with high energy electrons from the 6000V plate
voltage. The plate could burn off 1000 watts of power. Another
impressive tube you could use is a sheet metal plated triode called the
833A which powered AM radio for 70 years, many still on the air in 1KW
AM tranmitters. They are very cheap and reliable tubes. They also have
a great glass envelope for a fishtank...(c;