Microponics: The Smallest Possible Aquaponics System?

Hey ya'll! This is my first post, but I'm excited to get involved.

I used to live in a tiny apartment, so I wanted to design an aquaponics system that had a very small footprint in terms of square footage. What I came up with is what I'm calling the Microponics design and it allows someone to grow food via aquaponics in as little as two square feet of growing space. The full article is located here -> How to Grow Your Own Food When You Have Limited Space.

To create an example of this design, I lined up five of these 2 sq ft systems to create a linear garden which I called the Urban Food Wall. It was a successful project, although I'm eager to push the idea forward next time.

Feedback appreciated!

Great job! Depending on one's available space, it looks like the concept could be scaled up to match available space with a household's daily needs for fresh fish and veggies!

Hi John,

Feedback appreciated!

You may be interested to know that Microponics has an existing provenance.  In 2009, I adopted the use of the name to describe the integration of fish, plants and micro-livestock.

I wasn't the first to use it either...I learned subsequently that the name had also been used to describe a hydroponic method.

The process of suspending plants over a fish tank was pioneered by Ron Zwieg...about 40 years ago.  While Zwieg demonstrated that the process worked, it is not without its problems.  

I've seen lots of these small systems and my experience of them is that they almost never yield useful quantities of food...largely because of their small size...which makes them hard to manage and limited in terms of the plant-available nutrients that they can produce.  

Another problem is that, depending on the species, fish will eat the plant roots...particularly if their only alternative is algae.  Also, the nutrients generated by consumption of the algae would probably be insufficient to produce fruit on plants like tomatoes.

The development of Hoagland Solution, several decades ago, provided a stable consistent nutrient formula that became the basic standard for hydroponics growers.  These days, you can buy packaged nutrient solutions that suit the specific nutritional needs of almost every conceivable plant species.

If you found that the pH in your micro-system remained stable it was probably the consequence of not providing supplementary feed.  The nitrification process is actually naturally acidifying in most aquaponics systems.  There are exceptions to this rule but deep water culture is not one of them.

The suggestion that the fish "kind of takes care of itself since the fish eat algae" infers that the system is a type of biological perpetual motion machine.  While it's an attractive thought, it's unsustainable in practice.  To produce nutrients in any aquaponics system, you have to feed the fish more than just the algae.

I acknowledge your attempts to innovate and I'd be happy to discuss your work further with you.

I wrote The Urban Aquaponics Manual back in 2009 and, while it's a bit dated now, you can still access it - with my compliments.

Gary

Gary,

I'm delighted to be connected with such an expert in this area! Let's get into the details so I / we can learn from your expertise!

To set the stage: this is a specific design catering to a situation where you have about two square feet of growing space (in my case it was ten square feet so I put five of these systems in). So I'm talking about the most limited square footage use-case possible. When you say:

>> I've seen lots of these small systems and my experience of them is that they almost never yield useful quantities of food...largely because of their small size...which makes them hard to manage and limited in terms of the plant-available nutrients that they can produce.  

I would have to agree and disagree. Yes, someone simply isn't going to grow most of their food in a two square foot space. Agreed.

In terms of the availability of plant nutrients, my experience was that the plants loved the setup. I had seven foot tall tomato plants which were very, very productive. I also tested perennial plants in the form of orange trees and they too thrived in the setup.

There was no noticeable damage to any of my plants from the fish eating the roots. Keep in mind, though, that I was using lightly stocked goldfish. I'm not comfortable with the stocking density levels in a lot of the aquaponics designs I see because they remind me of small factory farms that happen to be under water.

>>  Also, the nutrients generated by consumption of the algae would probably be insufficient to produce fruit on plants like tomatoes.

We used a similar approach the previous summer to grow tomatoes and they grew to seven feet tall with a lot of fruit. I'll see what I can dig up in terms of pictures to share.

>> If you found that the pH in your micro-system remained stable it was probably the consequence of not providing supplementary feed.  The nitrification process is actually naturally acidifying in most aquaponics systems.  There are exceptions to this rule but deep water culture is not one of them.

Right. I think the whole goal with aquaponics / permaculture-aquaculture is striving for a design which doesn't require external inputs. This was largely achieved in the design I described here, although we did input significant amounts of water since the evaporation levels were high (the location was outside in Texas summer).

I also agree with what I think you are implying, which is that aquaponics designs with larger tanks are, in general, more stable. In this case, I was afraid to upgrade to even the size of a kiddie-pool because I was worried about collapsing the balcony at my rented apartment. So this design also reflects weight load considerations in an old and not well maintained structure.

>> The suggestion that the fish "kind of takes care of itself since the fish eat algae" infers that the system is a type of biological perpetual motion machine.

I felt like you were setting up a straw-person argument here by turning my approach into a bit of a characature. I never claimed anything close to a "biological perpetual motion machine." I'm merely noting that the fish not only survived, but they seemed to thrive in the sense that by the end of the summer they were roughly four to five times their original size. Of course, this was also related to their growth cycle. I did not keep control fish fed with feed for comparison purposes.

I did, however, keep a plant control group in the form of growing the exact same tomato plants in soil. The tomatoes grown using this system (which I had been calling microponics but I'm open to other possible names) grew over twice as fast as they did in soil. It’s hard to tell how much of this was due to aquaponics in general versus the specifics of the deep water design. I would like to do a direct comparison between the deep water approach and the flood-and-drain approach sometime in the future.

>> The process of suspending plants over a fish tank was pioneered by Ron Zwieg...about 40 years ago.

Just to be clear - I'm not claiming that I invented suspending plants over a fish tank, although it does bring up an interesting related topic about scaling up this general approach. I'd be curious to hear your thoughts about scaling this design up for use outdoors in a backyard of a single family home. I’m envisioning an above-ground swimming pool and then building a plant layer on top of it like a biological lid. Perhaps we can start a new thread to discuss your thoughts on that.

John, I like your experiments on your balcony. This very small scale gives me the impression I can do this too! I want to experiment with aquaponics. To get more understanding on it first (how to obtain a yield without too much input) I'd like to try a small system in my window sil. Thank you for showing your 'microponics'!

I'm delighted to be connected with such an expert in this area! Let's get into the details so I / we can learn from your expertise!

Thank you...but I'm not comfortable with being thought of as an expert.  What I do have is three decades of experience with micro-livestock and 12 years' experience in the design and operation of integrated aquaculture systems.  We all start out the same way...knowing nothing.  I learned from others and I try to pass it on.

In terms of the availability of plant nutrients, my experience was that the plants loved the setup. I had seven foot tall tomato plants which were very, very productive. I also tested perennial plants in the form of orange trees and they too thrived in the setup.

There was no noticeable damage to any of my plants from the fish eating the roots. Keep in mind, though, that I was using lightly stocked goldfish. I'm not comfortable with the stocking density levels in a lot of the aquaponics designs I see because they remind me of small factory farms that happen to be under water.

>>  Also, the nutrients generated by consumption of the algae would probably be insufficient to produce fruit on plants like tomatoes.

We used a similar approach the previous summer to grow tomatoes and they grew to seven feet tall with a lot of fruit. I'll see what I can dig up in terms of pictures to share.

Am I to understand that you grew "a lot of fruit" using nothing more than the nutrients generated by fish that were being fed nothing but the algae that grew on the the surfaces of the fish tank?  If this is the case, such outcomes are certainly outside of my experience and I would be very interested to know how you did it.

>> If you found that the pH in your micro-system remained stable it was probably the consequence of not providing supplementary feed.  The nitrification process is actually naturally acidifying in most aquaponics systems.  There are exceptions to this rule but deep water culture is not one of them.

Right. I think the whole goal with aquaponics / permaculture-aquaculture is striving for a design which doesn't require external inputs. This was largely achieved in the design I described here, although we did input significant amounts of water since the evaporation levels were high (the location was outside in Texas summer).

Have you tested source water?  It's not unknown for ground water, for example, to contain high levels of various pollutants...which can include nutrients.  In one situation, I was made aware of source water with nitrate levels of 160ppm.

I also agree with what I think you are implying, which is that aquaponics designs with larger tanks are, in general, more stable. In this case, I was afraid to upgrade to even the size of a kiddie-pool because I was worried about collapsing the balcony at my rented apartment. So this design also reflects weight load considerations in an old and not well maintained structure.

I do have concerns about very small systems from a biological stability perspective...but I understand the desire to experiment...I simply voiced the concern as a caution.

>> The suggestion that the fish "kind of takes care of itself since the fish eat algae" infers that the system is a type of biological perpetual motion machine.

I felt like you were setting up a straw-person argument here by turning my approach into a bit of a characature. I never claimed anything close to a "biological perpetual motion machine." I'm merely noting that the fish not only survived, but they seemed to thrive in the sense that by the end of the summer they were roughly four to five times their original size. Of course, this was also related to their growth cycle. I did not keep control fish fed with feed for comparison purposes.  

A perpetual motion machine is one which purports to keep functioning without any input...and thusfar no such machine has been shown to exist.  If I understand you correctly, you are claiming to have grown a "lot" of fruit fed by the metabolic wastes of fish fed on nothing more than algae...with no other inputs.  That is what prompted my 'tongue in cheek' reference to a "biological perpetual motion machine."  I intend no disrespect but, if it's as you say, then there has to be some other explanation...and my experience would suggest that your source water may be the culprit.

>> The process of suspending plants over a fish tank was pioneered by Ron Zwieg...about 40 years ago.

Just to be clear - I'm not claiming that I invented suspending plants over a fish tank, although it does bring up an interesting related topic about scaling up this general approach. I'd be curious to hear your thoughts about scaling this design up for use outdoors in a backyard of a single family home. I’m envisioning an above-ground swimming pool and then building a plant layer on top of it like a biological lid. Perhaps we can start a new thread to discuss your thoughts on that.

And I'm not suggesting otherwise.  I simply sought to explain that the growth of plants directly in a fish containing plants (like the term 'microponics') has a history...for what you might learn from previous attempts.

Zweig used 1500mm diameter translucent fibreglass tanks containing around 3000 litres of water and 7kgs of fish - that were fed at the rate of 3% of their bodyweight - to grow lettuce.  The 'inventor of record' of the first successful attempt to grow fruiting plants using the metabolic wastes of fish - in a closed loop - was Dr Mark McMurtry in 1985.

I'd be very happy to enter into a discussion of the type that you envisage.

Inge, I think this design might work well for you then!

Gary:

I forgot to mention last time that the link to your book was broken. Would you double-check it and potentially repost?

Also, I'm new to using this forum software, how are you highlighting my responses in white? I want to be able to do that!

Related to your question about water, I hooked up my kitchen sink to a 0.5 micron water filter and then used drip irrigation run to the hanging pots above to deliver the water. Due to my urban location, it was fairly easy to be diligent about the water quality. Watering the garden created a really, really cool simulated rain effect which I found to be quite calming. Video of that is here.

I was thinking about what you said about a perpetual motion machine... I think we forgot that electricity is a constant input, in addition to the water. Without the pumps running and pushing air through the system, it would not function. So we agree that inputs are required and it's not a perpetual motion machine. The point still stands, I think, that not having to feed the fish manually is a clear benefit of the design.

>>> Zweig used 1500mm diameter translucent fibreglass tanks containing around 3000 litres of water and 7kgs of fish - that were fed at the rate of 3% of their bodyweight - to grow lettuce.

I think this is the basic disconnect. I'm talking about a tiny (less than ten gallons) system with a few tiny goldfish inside. At that stocking density, algae seems to be sufficient to feed the fish. We can also assume that the fish were eating any bugs that landed in the water and some of the worms that I added later to turbocharge the bacterial growth. Once we scale aquaponics up to a larger unit size (i.e. the 3000 liters design you refer to), yes supplemental feed will be required at what is considered usual stocking densities. Again, I'm noting that I'm not comfortable with what would usually be considered a "normal" aquaponics stocking density and my goal in a larger system would be more of an aquaticulture approach like Paul advocates with a much lower stocking density.

>>> Am I to understand that you grew "a lot of fruit" using nothing more than the nutrients generated by fish that were being fed nothing but the algae that grew on the the surfaces of the fish tank?  If this is the case, such outcomes are certainly outside of my experience and I would be very interested to know how you did it.

See above. I think the different scales of system size are giving us a different frame of reference. Considering we are talking about 10-11 square feet of floor space, I think we can agree that this garden is quite lush and is producing usable food (see pictures here: Photo Gallery - the Urban Food Wall).

I tried to dig into the specifics of the output produced related to the tomato plant example. In the prior year's design, I grew one tomato plant in one 5 gallon bucket. I put water in the bucket, bubbled oxygen through the water, added the water from a stream, and added goldfish. I also added duckweed that time and the fish ate that as their food. The tomato plant grew to seven feet in height and produced at least 5 tomatoes (based on the pictures I found). I think we can agree that this is "a lot of fruit" for one square foot of floor space used. Here are the pictures from that tomato in water test in chronological order: Tomato Aquaponics Test. Here is the main picture with the results:



Note: the fish had to be removed once the root growth filled in a lot of the space. The duckweed was also not successful because it kept getting stuck on the roots when the water level dropped.

I'm enjoying the intellectual rigor of this conversation and hopefully this additional information is helpful. Have a great one!

Hi John,

Sorry 'bout the broken link.  Try this one....The Urban Aquaponics Manual

The software platform that drives permies.com has some hurdles (like the process of inserting links)....and some nice easy to use ones like QUOTE.   I'm still learning my way around here, so bear with me while I attempt to show you what I do.  

To quote entire posts, click on the Quote button in the top right hand corner of the post you want to quote....and that will insert the entire post into a new reply box.  The good thing about doing it that way is that it inserts the name of the poster.  This is handy for when you're responding to a particular post after several other people have replied....and it can be a bit confusing for people to follow.

When you click on that Quote button, your reply editor will reveal this....

John Oden wrote:

Gary:

I forgot to mention last time that the link to your book was broken. Would you double-check it and potentially repost?

Also, I'm new to using this forum software, how are you highlighting my responses in white? I want to be able to do that!

Related to your question about water, I hooked up my kitchen sink to a 0.5 micron water filter and then used drip irrigation run to the hanging pots above to deliver the water. Due to my urban location, it was fairly easy to be diligent about the water quality. Watering the garden created a really, really cool simulated rain effect which I found to be quite calming. Video of that is here.

I was thinking about what you said about a perpetual motion machine... I think we forgot that electricity is a constant input, in addition to the water. Without the pumps running and pushing air through the system, it would not function. So we agree that inputs are required and it's not a perpetual motion machine. The point still stands, I think, that not having to feed the fish manually is a clear benefit of the design.

>>> Zweig used 1500mm diameter translucent fibreglass tanks containing around 3000 litres of water and 7kgs of fish - that were fed at the rate of 3% of their bodyweight - to grow lettuce.

I think this is the basic disconnect. I'm talking about a tiny (less than ten gallons) system with a few tiny goldfish inside. At that stocking density, algae seems to be sufficient to feed the fish. We can also assume that the fish were eating any bugs that landed in the water and some of the worms that I added later to turbocharge the bacterial growth. Once we scale aquaponics up to a larger unit size (i.e. the 3000 liters design you refer to), yes supplemental feed will be required at what is considered usual stocking densities. Again, I'm noting that I'm not comfortable with what would usually be considered a "normal" aquaponics stocking density and my goal in a larger system would be more of an aquaticulture approach like Paul advocates with a much lower stocking density.

>>> Am I to understand that you grew "a lot of fruit" using nothing more than the nutrients generated by fish that were being fed nothing but the algae that grew on the the surfaces of the fish tank?  If this is the case, such outcomes are certainly outside of my experience and I would be very interested to know how you did it.

See above. I think the different scales of system size are giving us a different frame of reference. Considering we are talking about 10-11 square feet of floor space, I think we can agree that this garden is quite lush and is producing usable food (see pictures here: Photo Gallery - the Urban Food Wall).

I tried to dig into the specifics of the output produced related to the tomato plant example. In the prior year's design, I grew one tomato plant in one 5 gallon bucket. I put water in the bucket, bubbled oxygen through the water, added the water from a stream, and added goldfish. I also added duckweed that time and the fish ate that as their food. The tomato plant grew to seven feet in height and produced at least 5 tomatoes (based on the pictures I found). I think we can agree that this is "a lot of fruit" for one square foot of floor space used. Here are the pictures from that tomato in water test in chronological order: Tomato Aquaponics Test. Here is the main picture with the results:



Note: the fish had to be removed once the root growth filled in a lot of the space. The duckweed was also not successful because it kept getting stuck on the roots when the water level dropped.

I'm enjoying the intellectual rigor of this conversation and hopefully this additional information is helpful. Have a great one!

Now, that's good for quoting entire posts but, chances are that you only want to quote a section of a post.  This is handy when dealing with a structured response to a long post...like yours.  In that case, just cut and paste the text that you want to quote into your post...highlight it (in the reply) and click on the QUOTE button in the text editor task bar.....and you'll end up with something like this....

Also, I'm new to using this forum software, how are you highlighting my responses in white? I want to be able to do that!

I have no doubt that somewhere in the hundreds of thousands of posts on this forum there are clear instructions for doing these things...but hopefully this will get you going for now.

OK...now to the topic at hand...

Related to your question about water, I hooked up my kitchen sink to a 0.5 micron water filter and then used drip irrigation run to the hanging pots above to deliver the water. Due to my urban location, it was fairly easy to be diligent about the water quality. Watering the garden created a really, really cool simulated rain effect which I found to be quite calming. Video of that is here.

OK...so that almost rules out the possibility that your water contained nutrients that would have influenced the situation.  I say 'almost' because our water utilities don't always deliver on their promise of pure water.  Flint comes to mind and, just this week, two Australian water authorities reported allowing slugs of polluted water to get into the urban water supplies.  Anyway, for the purposes of your exercise, we'll assume that your water was/is nutrient-free.

I was thinking about what you said about a perpetual motion machine... I think we forgot that electricity is a constant input, in addition to the water. Without the pumps running and pushing air through the system, it would not function. So we agree that inputs are required and it's not a perpetual motion machine. The point still stands, I think, that not having to feed the fish manually is a clear benefit of the design.

Yes, any machine requires an input...some means of making it work....like fuel, electricity or a motive power source of some kind.  And you are right when you acknowledge the air being pumped in as an input...but that's not the only type of input that I'm talking about.  I think that where the issue is that we may be at cross purposes in our understanding of what "feeding the the fish" actually means.

Let me explain.

I think this is the basic disconnect. I'm talking about a tiny (less than ten gallons) system with a few tiny goldfish inside. At that stocking density, algae seems to be sufficient to feed the fish. We can also assume that the fish were eating any bugs that landed in the water and some of the worms that I added later to turbocharge the bacterial growth.

No, there's no disconnect.  It comes down to how you define "feeding the fish."  I get it that you weren't consciously putting a proprietary fish feed into the tank...but "that the fish were eating any bugs that landed in the water and some of the worms that I added later"...makes it very clear that they were eating something other than the algae that you believed was their sole nutrient source...and that (consciously or otherwise) you facilitated that input.

Once we scale aquaponics up to a larger unit size (i.e. the 3000 liters design you refer to), yes supplemental feed will be required at what is considered usual stocking densities. Again, I'm noting that I'm not comfortable with what would usually be considered a "normal" aquaponics stocking density and my goal in a larger system would be more of an aquaticulture approach like Paul advocates with a much lower stocking density.

I'd enjoy exploring Paul's 'aquaticulture' approach at another time....and I'm not at odds with your general proposition about aquaponics stocking densities.  Suffice to say, at this stage, biological systems of the same type have the same requirement for inputs....like nutrients, water, oxygen, hot/cold...regardless of their size.   I hope we've established that that's what happened in your case, too.  The bugs and worms are fish food and they were introduced into the system.  They, like the air, are inputs.

Let's continue....

I think the different scales of system size are giving us a different frame of reference. Considering we are talking about 10-11 square feet of floor space, I think we can agree that this garden is quite lush and is producing usable food (see pictures here: Photo Gallery - the Urban Food Wall).

I tried to dig into the specifics of the output produced related to the tomato plant example. In the prior year's design, I grew one tomato plant in one 5 gallon bucket. I put water in the bucket, bubbled oxygen through the water, added the water from a stream, and added goldfish. I also added duckweed that time and the fish ate that as their food. The tomato plant grew to seven feet in height and produced at least 5 tomatoes (based on the pictures I found). I think we can agree that this is "a lot of fruit" for one square foot of floor space used. Here are the pictures from that tomato in water test in chronological order:

I can accept that you grew food in that system that is depicted in the photos... and the issue is not one of scale but rather our different understanding of what constitutes fish food.  Fortunately...in terms of understand how your system really works...you provide the clue to the growth of the tomatoes when you say..."I also added duckweed that time and the fish ate that as their food."

Are you aware that duckweed can be up to 40% protein...and, that for some fish species, it would be a complete diet?

With that, I hope that I've convinced you that, in order to harvest outputs (fruit and vegetables...and algae) there has to be inputs...water, oxygen and plant-avaiable nutrients - that can come from the metabolic wastes of fish...so long as they are eating something (like bugs, worms and duckweed).

In furtherance of this goal, let me describe what would happen if you were to ensure no external inputs (like bugs, worms and duckweed)...with the exception of oxygen.  

Initially, the fish would eat the algae and they'd breathe and produce ammonia...and they'd poop and that would eventually become ammonia (and then other forms of nitrogen)...and the plants would be happy, too. Eventually, they'd eat all of the algae....and they'd start to transfer less of the metabolic wastes across their gills...and they'd poop less....and the algae would not have enough nutrients.   The plants would eventually show nutrient deficiences as the metabolic wastes from the fish diminished....and they'd be less happy for a while....till the fish died of starvation...and then they'd be happy again as they fed on the nutrients yielded by the decomposition of the fish.  That happiness would be shortlived, however, because once they'd used up the store of nutrients provided by the fish, growth would slow and fruiting would cease....and then the leaves would fall off and the plant would wither...and die.

Now, if we return to the proposition of growing food...in small spaces...using the metabolic wastes of fish to feed plants...using natural food inputs...the picture becomes far more optimistic....and I'd be delighted to explore that to your heart's content.

Interesting discussion, reading both points of view. I haven't tried aquaponics yet, but am new to growing stuff (at almost 48 years old), and have found a dream to be able to escape the corporate job in a few years and raise some livestock and grow food. Starting this summer with chickens soon, some microgreens in the basement, and this weekend getting some black raspberries and currants (plants). Aquaponics is on my list for the future though, and my wife is backing me up on this, as are my 5 yrold twins... my biggest inspiration to be home more and teaching them/learning all I can!

Thanks again for the interesting topic, and grow on!
Leif

Leif, FYI this design has been tested and works great for microgreens, assuming sufficient lighting.

Gary, the link worked this time and thank you for the quick software tutorial.

I think we've given this subject a thorough review, but just to hone in on the discussion of various food sources...

Re: Algae

Eventually, they'd eat all of the algae

You are underestimating how aggressive the algae grows in tanks with glass sides. The algae growth was much, much faster than the fish growth and I actually had to harvest out handfuls of algae just so the fish didn't get overwhelmed.

Re: Bugs

The bugs added themselves. My goal is creating a system where I don't have to manually add inputs. If nature wants to add the inputs for me, that meets my criteria of what I want for myself in terms of system maintenance. My goal is creating a system which does not require daily physical maintenance by a human being.

As an aside, in a slightly humorous earlier design, I had set up a bug zapper suspended over the fish tank to harvest bugs out of the air for the fish. This seemed to work well but I took it down because of safety concerns.

Re: Worms

Yes, I added the worms, just like I added every other component of the setup. I have no way of measuring this, but the worms seemed to cluster on the edge between the net pot and the water below in the tank. The net effect of this was that they seemed to multiply faster than they were being eaten since they had habitat in which they could hide. It's not clear to what extent the fish were eating the worms, although I did manually feed them worms occasionally during system maintenance. Again, if the system can generate worms faster than the fish eat the worms, this also meets my maintenance criteria.

So I guess what I'm coming to is that my goal is not "no inputs," but rather "no human inputs on a daily basis." It's more about my lifestyle and not wanting extra responsibilities that can't be automated.

Re: Duckweed

I found the duckweed to be surprisingly difficult to grow in these conditions due to the water level changes from evaporation and refill. From reading the literature, I had expected this to be an easy source of fish feed.

Re: "Natural Food Inputs"

I'm curious to know what you prefer to use for your fish food in your aquaponics systems. Of course I want my fish as healthy as possible.