After stumbling upon these incredible aquariums, I started dreaming about getting one again. But, they take a lot of maintenance and energy, and are noisy - in ways that nature usually isn’t and doesn’t. I discovered the Eco-Sphere, but to say the least, I find it inferior to the IAPLC-aquariums. Googling about, it seems most alternatives are equally small and unexciting. Why these limitations? Can’t I fill a 300 liter aquarium with the right combination of beautiful plants, bacteria, and fishes, seal it off and only provide lightning?
You can, but it is likely it will be an unstable system and you’ll regret sealing it off after all your fish die out.
Shrimps have a much lower bio-load than fish, as a general rule. If you wanted a six foot tank with two little fish in it, and the right plants, you probably could I suppose…
The pictures in the first link are all of very high maintenance set-ups, generally just put together for shows then dismantled after a few months, because they’re all pretty unstable, with plants that will require regular pruning, fertilising, and CO2 injection to look anywhere near that good for long.
You almost certainly couldn’t, for the same reasons that you can’t just build a bicycle with wheels 30 metres tall and expect it to be stable when ridden by a normal sized person. To much inanimate matter to be balanced by too little living biomass.
In a small volume of water there is a very small volume of essential nutrients and a small energy input. The autotrophs can’t get out of control because they are limited by the nutrient levels in the system, and the autotrophhs can’t get out of control because they are limited by the autotrophs.
If you have a bigger volume of water, you still need to maintain the same nutrients concentration, which means that there is more nutrient available in total. That means that you will get more autotroph growth, much more than two little fish can consume. That can only end in one of two ways. Either the autotrophs die, and as they decay the microbes consume all the oxygen in the tank, or else they don’t die, and as soon as it goes dark the living autotrophs consume all the oxygen in the tank.
It becomes very, very difficult to balance a larger terrarium as a sealed unit because the total amount of resources becomes large. That means that you have removed the limitation on at least one of the lifeforms, so it can grow out of control.