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Re: Filterless Plant Tanks

On 20 Jun 1997, Jamie Howton <jhowton at fotofab_com> wrote:

>I just read the article titled "Plants and the natural aquarium" by Doug 
>Valverde in the July 1997 issue of FAMA.  ...
>I would be interested in hearing any opinions.

I did a post on my tank, which is "filterless", back in February and I 
know that others on this list have quite a deal more experience with 
filterless tanks than I do. I've only been running one since September 
'96 but I'm happy about the way it is running.

Since my original posting is in the archives, I'll try and say something 
different and even more outrageous. I think filter manufacturers have 
successfully managed to misinform most aquarists and, as a result, nearly 
everyone now believes that biological filtratition is synonymous with a 
bacterial nitrification cycle!!! This is simply not true.

In reality heavy planting could be regarded as the ultimate biological 
filter. In "Dynamic Aquaria", Adey and Loveland espouse the use of algae 
scrubbers for filtration and provide some interesting arguments for 
relying on algae rather than bacteria as the primary filtration 
mechanism. One of Adey's points is that algae rather than bacteria are 
the main "filtration" system in natural water systems. From what I've 
read algae definitely seem to outnumber higher aquatic plants in terms of 
biomass, but there are habitats where higher plants rather than algae 
predominate. Plants provide the same virtues as algae, and they're a lot 
more attractive. Perhaps that's why filterless tanks are called "natural 

A heavily planted tank without the usual biological filter material is 
not a "filterless" tank. It is biologically filtered in a different, but 
more efficient, way. Plants not only remove ammonia as normal biological 
filtration does, but many other wastes as well. Artificial "wetlands" are 
now being used for reclaiming water polluted by heavy metals and also for 
treating human sewer waste. I don't think that there's anything your tank 
can produce in wastes that the plants can't handle, provided you have 

Now the fun advantages: "filterless tanks" are the only freshwater tank 
where your visitors pass very pleasing compliments about how lovely your 
filter looks without knowing that they're talking about your filter, and 
then proceed to tell you that you really can't run a tank "without a 
filter" and it's doomed to failure. Don't believe them when they do - 
tanks that rely on plants are extremely stable. It's also fun to confound 
the "experts" by proving that you can do the "impossible".

They also have one other great virtue - you never have to clean the 

I'm not knocking normal biological filters. They are extremely efficient 
and they are invaluable in many tanks. Depending on degree of planting 
and fish load they may also be completely superfluous in others

David Aiken