Self-maintaining Freshwater Aquariums

[celaeno]

what do you guys think about this self-maintaining freshwater aquarium?

link

as the description says, there are no water changes, no CO2 injection. only small fish, snails, sand, and live plants. sounds possible at first, but what about all the fish waste and the 3-month non-feeding period? i'm surprised the fish were able to last that long.

 

[Mikaila31]

Possible, but the tank would have to be lightly stocked. Plants can decrease nitrate, mine drops from 20ppm to 10pmm in 7 days in a densely planted tank, and plants don't need CO2 only if you have higher lighting. Fish waste would be used by the plants similar to the way manure is used on fields. And 3-months of no feeding, just means no food was put in the tank. Fish especially herbivores, would have no trouble surviving in a planted tank that is not cleaned.

 

[CFC]

But where do the organc acids released by the break down of organic matter in the tank go? Without some way of diluting these acids with fresh water sooner or later the KH is going to drop to zero and the pH is going to start swinging about like a yo yo, pH dropping at night when the plants start using O2 instead of CO2 from the water and rising again when the lights come on. These pH changes happen all the time over 24 hour periods in the wild but rainwater dilutes the acids so it never reaches extreem levels, in a tank it could get dangerously low very quickly.

 

[PRW1988]

It's a possible tank, however I find it a little curel to allow the fish to swim through their own waste. Yes, the plants help to remove some of this, as does evaporation (which I see nothing about in that link, I assume the person topped the water up every once and a while). The fish that he shows are low waste output and stay small that's why they're not dying quickly. My theory is that the tank will eventually crash.