Many aquarists indeed discover that their aquarium works just as well without its filter.
The first reactions, reluctantly, were to concede that it could work provided there are very few fish.
But, once again, the experience showed the opposite.
Some had already taken the plunge and also removed the filter from their aquarium... without any unfortunate consequences.
Aquarium filters are attributed two functions, a mechanical function and a biological function.
In the absence of a filter, the first function is no longer guaranteed, but the biological function is perfectly ensured without a filter.
It doesn't need one at all, like in nature, the entire aquatic environment is a very rich microbiome, and bacteria populate it by the billions.
An aquarium rich enough in microbial diversity is a filter in itself, these bacteria ensure all biological cycles, including the famous nitrogen cycle.
This cycle generally consists of transforming organic matter into nitrites, then into nitrates, and this can be done with or without a filter, it works just as well.
To do without a filter, it is therefore enough to allow a maximum microbial diversity to settle.