# PLANTS versus FILTERS



## Grizzle Fish (May 29, 2014)

Hello folks,
I'm interested in opinions on doing away with the bio function of my filter.

I just finished reading a fairly new article by By Diana Walstad written July 2014 "PLANTS versus FILTERS".

The question that this article presented to me was whether I should run biological filtration in my upcoming 10 gallon El Natural tank. My understanding of Diana's article was that plants by themselves could take care of eliminating ammonia and ammonium produced by the fish, (presumably if they were not over stocked). That being the case, and assuming I had a sufficient amount of plants, I would theoretically never see nitrates occur, as the cycle would end there. Again, so I would assume.

One question I have is, if both plants and bio-filter exist together, which one would be the most efficient in metabolizing the available ammonia/ammonium? I suppose it depends to a degree on the size of the bio-filter. The problem would be if the bio-filter wins out and expeditiously uses up all of the available ammonia/ammonium. --In that case, based upon the article, the plants would be forced to metabolize nitrates rather than ammonia/ammonium, which would cause them to expend far more energy, as they would have to convert the available nitrate into ammonium first in order to metabolize it, which would lead I assume to slower growth rates.

The only past experience I have had with a planted tank was back in 1964. My neighbor gave me a 5 gallon tank for my eighth birthday with a bunch of stem plants, a few guppies in it, and an air pump for circulation. Other than topping up the water I didn't do water changes on the tank. The plants grew very well, and the fish were active and also did well. I have never since had such a maintenance free aquarium! I remember how clear the water always was and how I had to keep cutting away the plants because they grew so fast. It's eventual demise was that it became overrun by snails. :-(

I'm very interested in what you folks may have to say on this subject if you care to comment.

Thank you,
~Grizz


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## Michael (Jul 20, 2010)

Consensus seems to be that in a well maintained planted tank, the plants out-compete bacteria for ammonium, to the extent that planted aquaria never go through the "cycle" in the same way that fish-only tanks with biological filtration do. Good water circulation is important so that ammonium is distributed well throughout the tank to facilitate uptake by the plants.

I like to keep biofilters running on my tanks as insurance if some accident occurs--overfeeding or a big fish dies and I don't see it. I also like to keep more fish in my tanks than Walstad does. But most of the time I suspect that the filters just circulate the water and the plants do most if not all of the biofiltration.


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## Grizzle Fish (May 29, 2014)

Thanks Michael, that was my main concern, the filter out-competing the plants.
Looks like I'm about to buy some plants and go for it.
Thanks again for all your help. APC Rules,
~Grizz


Sent from my iPhone using Tapatalk


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## HDBenson (Sep 24, 2014)

I agree with Michael. In theory a Walstad set-up does not need a conventional filter of any sort. She suggests the use of filters for circulation on larger tanks. However, I too use filters on my Walstad set-ups JUST for circulation and as a back-up... just in case. I like using internal filters for this purpose. With their slim design they are easy to hide and quiet!


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## Grizzle Fish (May 29, 2014)

Thank you HD.


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## Zapins (Jul 28, 2004)

Grizzle Fish said:


> The question that this article presented to me was whether I should run biological filtration in my upcoming 10 gallon El Natural tank. My understanding of Diana's article was that plants by themselves could take care of eliminating ammonia and ammonium produced by the fish, (presumably if they were not over stocked). That being the case, and assuming I had a sufficient amount of plants, I would theoretically never see nitrates occur, as the cycle would end there. Again, so I would assume.


Yes this is probably true. Plants would use up all the nitrogen made by the fish, though all the bacteria would never be completely starved and totally die out. The main issue with having no biological filtration isn't really with nitrates and ammonia it is with removing organic molecules out of the water.

Total dissolved solids build up as plants, bacteria, fish cells, etc die and decompose in the water. These organic molecules are extremely complex and plants cannot break them down much less even use them. Over time they build up in the water and can foul it and reduce fish health and even promote algae (which can actually use it to grow). Having a biological filter going greatly helps reduce this organic waste build up by allowing the bacteria in it a chance to digest the complex organics and reduce them back to things like nitrate and ammonia which can be used by plants. Without providing a space for these bacteria to live inside the filter you will not prevent their growth, they will just change locations and start living inside the tank, covering the surface of the glass, plants etc... This can cause the appearance of the tank to change and become more orange or dark, sometimes even leaving filmy residues on surfaces. Also, since the surface area of the tank is much smaller than the filter floss/sponge that would be in the filter itself the bacteria are not as exposed to the organics in the water and aren't as efficient, so the organics tend to build up over time and cause more changes in the water.



Grizzle Fish said:


> One question I have is, if both plants and bio-filter exist together, which one would be the most efficient in metabolizing the available ammonia/ammonium? I suppose it depends to a degree on the size of the bio-filter. The problem would be if the bio-filter wins out and expeditiously uses up all of the available ammonia/ammonium. --In that case, based upon the article, the plants would be forced to metabolize nitrates rather than ammonia/ammonium, which would cause them to expend far more energy, as they would have to convert the available nitrate into ammonium first in order to metabolize it, which would lead I assume to slower growth rates.


Surprisingly most aquatic plants (and plants in general) do not use ammonia very well. It is just as toxic to plants just as it is to fish and animal life. Plants have a difficult time preventing it from entering cells where it causes damage and messes up the H+ balance, especially in aquatic plants which lack a wax cuticle like terrestrial plants have. Some species can use ammonia and grow well with it but in general nitrate is the preferred source of nitrogen.


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## TropTrea (Jan 10, 2014)

This debate I think goes back to some of early aquatic books that were wrote back in the 1950's even. The old theory being if the aquarium is perfectly balanced things like water changes and biological filters become less and less important. However the secret is that no one can say 100% what is perfectly balanced.

In nature you always have a circulation of new fresh water coming in from the streams and rivers as snow and ice melts in higher elevation plus rain water. If nature is the perfect example of the balanced aquarium it is extremely difficult to duplicate these conditions. Stocking levels of most aquariums is also many times heavier than what is in nature when you look at the whole picture. 

Yes you can drastically reduce the need for extra biological filtration however can you completely eliminate the need for it? I seriously doubt it can be done in a practical way.


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## Grizzle Fish (May 29, 2014)

Zapins said:


> Yes this is probably true. Plants would use up all the nitrogen made by the fish, though all the bacteria would never be completely starved and totally die out. The main issue with having no biological filtration isn't really with nitrates and ammonia it is with removing organic molecules out of the water...


Ah, I see. I was under the impression that the filtration of organic waste was accomplished solely by mechanical filtration. Thanks Zapins for pointing that out to me. I'm always stoked to learn important aspects such as that. Makes me happy!



Zapins said:


> Surprisingly most aquatic plants (and plants in general) do not use ammonia very well. It is just as toxic to plants just as it is to fish and animal life. Plants have a difficult time preventing it from entering cells where it causes damage and messes up the H+ balance, especially in aquatic plants which lack a wax cuticle like terrestrial plants have. Some species can use ammonia and grow well with it but in general nitrate is the preferred source of nitrogen.


Regarding the statement directly above (ammonia), there seems to be some disagreement on that subject based upon the article that I read by Diana Walstad. I really hope it's ok to quote a portion of that article for sake of discussion. If not I sincerely apologize to DW. ~Grizz



Diana Walstad said:


> PLANTS versus FILTERS
> Ammonium and nitrite are detrimental to fish health. Most hobbyists rely on filters (i.e., "biological filtration" or nitrification) to remove these toxins from the water. They do not consider using plants. Even hobbyists with planted tanks underestimate plants in terms of water purification. For they assume that plants mainly take up nitrates as their source of N (nitrogen).
> However, the truth is quite different. Scientific studies have shown repeatedly that the vast majority of aquatic plants greatly prefer ammonium over nitrate. Moreover, they prefer taking it up via leaf uptake from the water, rather than root uptake from the substrate. Thus, plants can-if given the chance-play a major role in water purification.
> 
> ...


I would encourage anyone interested in this thread to read that entire article I linked to above PLANTS versus FILTERS. It's not very long but is really informative. I also purchased her book "Ecology of the Planted Aquarium". I bought the digital version and read it on my phone. I kind of regretted not buying it in paper form, as it would have been a lot easier to go back and reference the data in paper form.

~Grizz


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## Grizzle Fish (May 29, 2014)

TropTrea said:


> This debate I think goes back to some of early aquatic books that were wrote back in the 1950's even. The old theory being if the aquarium is perfectly balanced things like water changes and biological filters become less and less important. However the secret is that no one can say 100% what is perfectly balanced.
> 
> In nature you always have a circulation of new fresh water coming in from the streams and rivers as snow and ice melts in higher elevation plus rain water. If nature is the perfect example of the balanced aquarium it is extremely difficult to duplicate these conditions. Stocking levels of most aquariums is also many times heavier than what is in nature when you look at the whole picture.
> 
> Yes you can drastically reduce the need for extra biological filtration however can you completely eliminate the need for it? I seriously doubt it can be done in a practical way.


Thanks TropTrea,
In general I believe you are correct in your statement. I can say that my experience many years ago was having a heavily planted tank, I mean, the plants grew so much that they wound up taking up about eighty percent of the available space in the tank. I thought having all of that plantage in there looked really cool and I trimmed the plants just enough for the fish to have some swimming room. Being a kid at the time I didn't do water changes, but I did keep the tank topped up. I have a good memory of just how clear and clean the water always was and the fish being healthy. I had a little air pump for circulation, that was it.

Now, that said, that did not go on indefinitely, as some snails unfortunately hitchhiked a ride on the plants. Over time they multiplied over and over until it was insane and ruined the tank. So I really couldn't say how long those water conditions would have lasted if that problem wouldn't have occurred.

I would have to assume based upon the posts from you all, that the prudent thing to do would be to use a bio filter, and that there would most likely not be a good reason to not use one, save perhaps for the coolness factor of being able to say that you run a successful aquarium without any filtration whatsoever! Perhaps some time in the future??? 

~Grizz


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## AEWHistory (Jul 6, 2008)

I'd like to add my 1/50 of a buck here. I've run my fair share of tanks with only a sponge and plants, some with just plants, and so on. But for my money I like using both. Even if the filter itself provides only a modest boost to the "filtering" abilities of the plants, the filter is still a fantastic place to place a scud colony. This is a double positive in my book. They scavenge a lot of junk that comes into the filter and themselves can become live food for the fish. I also like to add trying to cultivate a colony of worms in the substrate. It adds a modest little cleanup crew and keeps the fish very happy and active.

One last note: a side advantage of a filter is that when the pads are filth encrusted, instead of throwing them out they can be converted into worm cultivation platforms with some built in detritus for the little buggers to feast upon. While this isn't the point of the filter, per se, I've always been attracted to the biological cycle of it all.


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## AEWHistory (Jul 6, 2008)

TropTrea said:


> This debate I think goes back to some of early aquatic books that were wrote back in the 1950's even. The old theory being if the aquarium is perfectly balanced things like water changes and biological filters become less and less important. However the secret is that no one can say 100% what is perfectly balanced.
> 
> In nature you always have a circulation of new fresh water coming in from the streams and rivers as snow and ice melts in higher elevation plus rain water. If nature is the perfect example of the balanced aquarium it is extremely difficult to duplicate these conditions. Stocking levels of most aquariums is also many times heavier than what is in nature when you look at the whole picture.
> 
> Yes you can drastically reduce the need for extra biological filtration however can you completely eliminate the need for it? I seriously doubt it can be done in a practical way.


This isn't so difficult: You just need a 3,000,000,000 gallon aquarium. I think PetSmart carries this, no?

Oh... You said practical.... Never mind.

But can you imagine the sump on that sucker!?


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## BruceF (Aug 5, 2011)

From what I have read it seems “balanced” Aquariums were actually an early Victorian concept as they tried to figure out how to keep things alive in the first place. As someone who often keeps aquariums without filters or with simple sponge filters I would say the mechanical side of the filtration is very important. Much of this debris can be removed with frequent water changes but that becomes increasingly difficult as the plants grow in. Without fish and perhaps more importantly fish food it isn’t all that difficult to keep this kind of environment thriving, especially since 100% water changes are possible. I tend to think the real problem in this kind of tank is the lack of oxygen, the old heterotrophic versus autotrophic bacteria thing. Anybody who keeps a compost pile knows that aerating the pile will breakdown the organic waste at a much faster rate and perhaps more importantly will keep the pile from smelling foul. Even just a power head or an air pump will help keep things “cleaner.”


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## Michael (Jul 20, 2010)

Zapins, thanks for the reminder about dissolved organics. I know you have done a lot of research on these, especially their role in algae growth.

In Walstad's article, she carefully uses the term ammonium rather than ammonia. These are closely similar molecules that can change into each other back and forth. In aquaria, this change is largely influenced by pH. Lower pH encourages the formation of ammonium, higher pH encourages the change into ammonia.

The importance to us is two-fold. Ammonia is more toxic to plants and animals than ammonium. Plants easily use ammonium but not the toxic ammonia. To give a practical example, Rift Lake cichlids are normally kept in high pH unplanted aquaria. Care guidelines for these fish often say that one must maintain very clean water, with frequent water changes and big, efficient biofilters. One of the main reasons is that the high pH favors the formation of the more toxic ammonia.


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## Grizzle Fish (May 29, 2014)

Thanks AEW and Bruce for your posts. I appreciate the helpful and experienced information that the both of you provided. Bruce, that does put the topic into perspective for me. Good job articulating that message.

AEW, I'll have to think about adding worms. I recently had a nasty experience with a mosquito infestation in one of my tanks. The gravel was filled with hundreds of squiggly red worm like larvae that I had to rid the tank of. I never thought of myself as squeamish before, but I came close to revisiting my lunch on that one. Shamed me, lol. BTW, nice icon you have there. One of my most favorite albums, used to know all the lyrics by heart. Not going to sit this one out though.

~Grizz


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## Grizzle Fish (May 29, 2014)

Michael said:


> Zapins, thanks for the reminder about dissolved organics. I know you have done a lot of research on these, especially their role in algae growth.
> 
> In Walstad's article, she carefully uses the term ammonium rather than ammonia. These are closely similar molecules that can change into each other back and forth. In aquaria, this change is largely influenced by pH. Lower pH encourages the formation of ammonium, higher pH encourages the change into ammonia.
> 
> The importance to us is two-fold. Ammonia is more toxic to plants and animals than ammonium. Plants easily use ammonium but not the toxic ammonia. To give a practical example, Rift Lake cichlids are normally kept in high pH unplanted aquaria. Care guidelines for these fish often say that one must maintain very clean water, with frequent water changes and big, efficient biofilters. One of the main reasons is that the high pH favors the formation of the more toxic ammonia.





Zapins said:


> Surprisingly most aquatic plants (and plants in general) do not use ammonia very well. It is just as toxic to plants just as it is to fish and animal life. Plants have a difficult time preventing it from entering cells where it causes damage and messes up the H+ balance, especially in aquatic plants which lack a wax cuticle like terrestrial plants have. Some species can use ammonia and grow well with it but in general nitrate is the preferred source of nitrogen.


As I read DW's article I assumed that throughout it she was specifically referring to ammonium. But at the end of the article there is a note that states that whenever she refers to ammonium, that she is also referring to ammonia. In that note she does however refer to ammonia as "toxic". Hence my confusion.

She states that the levels of ammonia present in relation to ammonium are 0.57% at pH 7.0, and go up to 5.4% at a pH of 8.0.

My first interpretation of her article was that she was suggesting that one could do away with the mechanical bio-filter. I shouldn't have jumped to that conclusion though as she never stated that. The article was intended to provide information about how aquatic plants filter the water. I see from her study that the relationship of ammonia to ammonium is fairly small, but it is indeed present and she does refer to ammonia as toxic. I get that now, I can be thick as a brick sometimes.  So there's the case for including a bio-filter, the bio-filter will remove ammonia!

This discussion was very helpful to me, as, if I had never made this post, I would have gone ahead with some misconceptions. Considering my first planted tank almost 50 years ago, I most likely had a good balance of fish and plants where the plants were able to assimilate the ammonia along with the ammonium without too much detriment to themselves, which kept my fish happy. So I would conclude from that experience that with the correct balance of fish and plants, you could, at least for a while have success without a bio filter. That said, a better yet environment and more sustainable environment would be provided with added mechanical bio-filtration to remove ammonia and organic waste. From what I have read about osmotic regulation in fish, frequent water changes are also necessary for optimal health of your fish.

Thank you all very much for your contributions to my thread!!!

~Grizz


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## TropTrea (Jan 10, 2014)

BruceF said:


> From what I have read it seems "balanced" Aquariums were actually an early Victorian concept as they tried to figure out how to keep things alive in the first place. As someone who often keeps aquariums without filters or with simple sponge filters I would say the mechanical side of the filtration is very important. Much of this debris can be removed with frequent water changes but that becomes increasingly difficult as the plants grow in. Without fish and perhaps more importantly fish food it isn't all that difficult to keep this kind of environment thriving, especially since 100% water changes are possible. I tend to think the real problem in this kind of tank is the lack of oxygen, the old heterotrophic versus autotrophic bacteria thing. Anybody who keeps a compost pile knows that aerating the pile will breakdown the organic waste at a much faster rate and perhaps more importantly will keep the pile from smelling foul. Even just a power head or an air pump will help keep things "cleaner."


Yes it may have begun in the Victorian ear however one of my first aquarium books was called "The balanced Aquarium" which was written prior to 1963 when I got it. The goal of the book was was discussing a neat zero maintenance balanced Aquarium. However it did encourage water movement and supplying air with air stones. It also recommended the use of box filters with filter floss and carbon that was changed very regularly.

There was considerable talk about the "good" bacteria in the tanks as well. This being one of the big key for the balance. It claimed that every undisturbed surface in the aquarium is a breeding ground for the good bacterias. The gravel when not disturbed is a big key here with there recommendation of using very fine sand at it has a greater surface are per its volume compared to coarser sands.

There was even a section on lighting.

Many of the principles in the book are still proven to be true. However the supporting devices like filter have come a long way since then. Advances were made since then some beneficial other were not like under gravel filters. But to this day even the most elaborate systems cannot mimic completely the one nature gives us.


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## TropTrea (Jan 10, 2014)

Grizzle Fish said:


> So I would conclude from that experience that with the correct balance of fish and plants, you could, at least for a while have success without a bio filter. That said, a better yet environment and more sustainable environment would be provided with added mechanical bio-filtration to remove ammonia and organic waste. From what I have read about osmotic regulation in fish, frequent water changes are also necessary for optimal health of your fish.
> 
> Thank you all very much for your contributions to my thread!!!
> 
> ~Grizz


Even the old book pointed out that a good balance will reduce but not eliminate the need for water changes. They recommended a minimum of 10% every week. However I have seldom seen a tank with the low number of fish that they recommended. If I recall correctly in a ten gallon tank they only recommended about 4 guppies maximum. They had a very complex formula that surface are of the tank rather the volume as well a temperature and several other factors. At the time of reading it I had a 10 gallon guppy tank and applied the formula to the fish I had the tank and found I really needed a 55 gallon tank for those guppies.


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## JKUK (Feb 16, 2007)

Zapins said:


> Total dissolved solids build up as plants, bacteria, fish cells, etc die and decompose in the water.


I would just like to add that in my experience this is not always the case with unfiltered Walstad tanks. In fact the TDS has actually fallen slightly in most of my tanks over time. The only time I see this happening is in open top tanks where I'm constantly adding water due to evaporation.

This is what I enjoy about Walstad tanks, everything is in natural equilibrium.


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