# Plants act as bio filtration?



## JESTERX626 (Sep 18, 2006)

I hear if plants are growing heathily it really acts as bio filtration? All i heard before is it aids in keeping the water clean but how come I never heard of this concept before? How does that work? I mean does it fully replace the job of bacteria in a filter?


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## GillMan (Feb 22, 2005)

It doesn't replace it, it adds to it. Bacteria settle on all surfaces in the filter and in an aquarium including on plants. The filter media provides orders of magnitude more surface area which, with a constant flow of oxygenated and "untreated" water, helps in cultivating large concentrations of bacteria provided you have a large bioload.

I suppose with a very small bioload, you can get by without a filter as long as you have good water movement. Plants that are growing under optimal conditions will remove nitrogenous, phosphoric and carbonic waste products from the water colunm. They'll even alter the water hardness as calcium and magnesium are taken up.


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## AndyT. (Jun 28, 2006)

Have you ever seen pictures or drawings of Victorian aquariums from the 1800's? They were successfully keeping fish for years without electricity. If you look at the pictures all of the aquariums are heavily planted. I remember reading an article in Aquarium Fish Magazine maybe 10 years ago on fishkeeping back then. Apparently for water movement they recommended that once a day you stick your hand in the aquarium and agitate the water for a minute or two! 

So, yes, if an aquarium is very heavily planted you can keep a light bioload of fish without any other filtration. Gillman is right, the plants supplement the bacteria in removing the nitrogenous wastes.


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## Laith (Sep 4, 2004)

Which is why you don't have a nitrogen cycle when you start a tank that is heavily planted from day one.  

It is also why in well lit, heavily planted tanks with CO2 injection, we need to *add* nitrates and phosphates or the plants would starve...


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## CherylR (Aug 12, 2004)

Aquatic plants preferentially take up ammonia (fish waste) over nitrate. So the bacterial cycle is limited by good plant growth. Or bypassed, if you will. Depends of course on your fish load, but many of us don't deliberately cultivate a bacterial presence in the tank.

For example, in my 18-gallon tank I have a sponge over the intake of my powerhead. This is the only filter on the tank. I happily rinse it in tap water every week and completely ignore all the dire warning about disturbing the biological filter because the tank is very heavily planted and growing well. The fish in this tank are about five years old. The cherry barbs still spawn regularly. Happy fish!

Cheryl


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## Jared Bozeman (Nov 21, 2005)

> Aquatic plants preferentially take up ammonia (fish waste) over nitrate.


very true. and although it's not that applicible in traditional high light tanks that have water changed regularly, diana walsted points out that plants work very as filters of other problematic things, like certain heavy metals. walsted's methods, while unconventional, let the plants do practically all filtration.


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## TWood (Dec 9, 2004)

The main reason I started doing plants was to maintain water quality for the fish. Bacteria populations drop off quickly below 6.5 pH, so the plants are all that's left in a high-concentration of CO2 injected setup.


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