Filterless Tanks? Anyone Got One?

Spishkey · Sep 22, 2008

i remeber seeing a post on here a while back that i think started a little debate about filterless tanks and if they work. it really caught my attention!

can anyone point me in the direction of that post or would it be long gone now?

im hoping to set up a small heavily planted tank with no filter as im very interested to see if it works.

is there anything special i need (specialist lighting or is normal ok?) any certain plants that are better than others?

gravel, soil or sand? does it matter? do these planted tanks go through a cycle process too?
do i need a powerhead for circulation? an airline? or should the plants provide enough oxygen?
i remeber on the thread there was a book recommendation too, diane someone im sure but cannot for the life of me remeber the title or last name so not getting much in search results

Mr Bliss · Sep 22, 2008

Diana Walstad, you can easily google up plenty of her articles and tank specs. The Walstad method is essentially a low-tech planted tank, where you plant heavily, use nutrient rich natural soil, moderate light, no CO2 injection. I would add a DIY CO2 system if I were to use her method, though.

You do need a small powerhead for circulation, both for oxygen and make sure nutrients are constantly available for all the plants. No airstone though. I doubt plants will produce enough oxygen unless you have a high light and CO2 injection (in which case they do produce all the oxygen your fish will need and more), but water circulation from the powerhead is all you need to keep the water oxygenated.

I started my current planted tank as a filterless tank, and early tests showed that a biological filter wouldn't be necessary as the plants consumed ammonia faster than a mature filter would (this is a 3 WPG tank with CO2 injection), so I just went ahead and started adding fish. As soon as the first inhabitant (a bristlenose) had arrived I realized I need a mechanical filter though, because he kept disturbing the surface and causing unsightly debris to float up. It also took forever for the water to clear up every time I uprooted or planted something. For that purpose, I'd recommend you get some kind of a sponge filter at the very least.