Removing the filter in an aquarium: what if it were possible?

More and more enthusiasts are rediscovering a simpler aquarium keeping by doing without a filter.

In the early 2000s, the success of the trash bin aquarium marked a quiet but deep break in aquarium knowledge.

Some enthusiasts began placing their fish outdoors in the garden for the summer, in simple plastic bins or water collectors! The idea was to offer them a bit of real wild life after a winter in the aquarium, less stress and less feeling of captivity.

No heating (and thus irregular temperatures), no aeration, no filter… nothing matched the aquarium keeping standards.

Yet, against all odds, it was observed that the fish often grew much better and were healthier under these rather… surprising conditions!
For the most experienced aquarium keepers, it was a mystery, some even struggling to believe what they saw.

But the essential question, still much debated today, was: how could these bins work without any filter, when our aquariums always have one?

The first reactions, hesitantly, conceded that it could work "provided there are very few fish".

But again, experience showed the opposite. Especially since some had already taken the step and also removed the filter from their aquarium… without any harmful consequences!

While an aquarium is sold with its filter, how was such a thing possible?

Filters in aquariums are attributed two functions.

• a mechanical function (removing particles and impurities from the aquarium)

• and a biological function (breaking down waste and ensuring the nitrogen cycle).

Without a filter, the first function is no longer fulfilled.
Waste settles on the bottom instead of piling up in the filter media. Just as it does in nature.

However, the biological function is perfectly fulfilled without a filter.
It does not need one at all. As in nature, the entire aquatic environment is a very rich microbiome, and bacteria populate it by the billions, both in the water and on the walls, plants, soil… Every grain of sand is coated with a bacterial film made up of countless microorganisms.

Thus, an aquarium rich enough in microbial diversity is a filter in itself.

These bacteria carry out all biological cycles, including the famous nitrogen cycle.
This cycle generally consists of transforming organic matter into nitrites, then into nitrates (less harmful). And this happens just as well with or without a filter!

On the other hand, believing that the filter does more than that (for example, reducing nitrate levels) is a stubborn belief…

With or without a filter, the amount of nitrates in an aquarium is exactly the same. Only plants can make them disappear by consuming them.
The stronger the light intensity, the more intensely they will do so.

This explains why measurements taken in planted trash bin aquariums revealed surprisingly low nitrate levels. And this without a filter.
Again, just like in nature.

However, it is true that the mechanical role of the filter helps avoid deposits on the bottom that some might find unsightly, by sucking up and retaining suspended particles. But a simple siphoning of the bottom two or three times a year is enough to solve this problem, which is ultimately only aesthetic.

To do without a filter, it is therefore enough to allow a maximum microbial diversity to establish itself.
This is the role of the Zollabox start-up which brings to an aquarium or a trash bin aquarium, or even a pond, the millions of microbial species included in its three doses (and not a cloned strain!), thus forming a rich entourage so precious for aquatic balance, a maximum biodiversity.

There is no doubt that we are on the verge of important discoveries about this aquatic microbiome, about which research is still in its infancy.

Extreme cleanliness is the enemy of the aquarium!

Another advantage of doing without a filter is that it removes the current and suction that bother certain species. This current must even be absolutely avoided in aquariums without fish, populated by aquatic micro-fauna and plants. A filter would then suck up your ostracods, your daphnia, your Blackworm and even sometimes the water lice which are precisely what make these meditation aquariums so prized and so calm so interesting.

The old "under sand" filters, connected to a simple small air pump and which created an imperceptible current by just passing water through the soil, were already using this ability of the aquarium to use its own microbiome to stay healthy!

Then came the era of technology at all costs.

Sometimes to the point of absurdity...

To learn more about natural aquarium keeping, do not forget Mattier’s blog.