Building a Home Aquaponics System: The Basics | Hacker News Reader

Building a Home Aquaponics System: The Basics

thissmarthouse.net

254 pointsohjeez74 comments

The author glosses over the true source of the magical, "free" fertilizer: "some fish food." You have to feed the fish. I have never seen an aquaponics zealot do the math on the cost per unit of fish food versus the cost per unit of fertilizer. Intuitively, complexity and costs could be reduced greatly by removing the fish component, i.e. hydroponics.

Is it possible to feed the fish using waste from the plants?

If they're meat plants. According to this article (http://animal-world.com/encyclo/fresh/Knifefish/BlackGhostKn...), they're carnivores who can eat pellets. Reading this entire page, it looks like Black Ghost Knifefish are not trivial to keep happy and healthy, and will eventually need 100 gallons of water. While I would argue that it's irresponsible to treat any fish as a mere fertilizer producer, this fish may be especially miserable for its limited life.

Hmm, is there some other kind of fish better suited to this type of system? Some kind of fish that could naturally survive on the plant waste? Maybe not even the waste in the water but some other form of biomass from the rest of the system?

e: Sibling comments seem to suggest Tilapia or Rainbow Trout.

Not sure what you're proposing, but something has to go into the system (fish food or fertilizer) if you're going to be taking things out (food). If the fish are living off of the plants, then you need to feed the plants. If the plants are living off of the fish, then you need to feed the fish. Something something Law of Conservation of Mass and Energy something something.

Yeah good point, that must be why all ecosystems fail without human intervention.

In a natural ecosystem, nothing is taken out, whereas in this one, food is supposed to be removed from the system, making inputs necessary.

Sunlight and air are inputs though. Most of what you take our of the system comes from changing H2O and CO2 from the air into a different form using energy from the sun.

There is the potential various micro nutrients, and minerals. However the vast majority of what the system needs is air and sunlight.

Right, but nutrients and minerals are still being regularly removed from the system--they need to be put back in order for the system to function. Their mass relative to the mass of other inputs doesn't change the calculus.

Right. Just ecosystems wherein humans regularly remove a considerable portion of the overall biomass. Like a garden.

Yeah conservation of matter, you need minerals other than carbon, oxygen and sunlight to make food therefore if human in the loop is introduced you need to take the human byproducts into the system as well

His Black Ghosts are in a 150-gallon tank. They'll be quite happy.

Why do you feel that using a fish for fertiliser production is irresponsible? It seems to be an effective way of using something that the majority of people who keep fish treat simply as a waste product.

I use the water from my tank's water change to water all my plants in the house. I can fill almost three watering cans which is enough for two waterings of the various decorative plants and herbs I have (I don't have any vegatables or this surely wouldn't be enough). And that's just a measly 10 gallon aquarium.

Agreed, this is why IMO it's much better to set up a tank with fish you can eat (Tilapia was mentioned in the article, but I've seen rainbow trout setups as well).

Makes paying for fish food a little better, because you get a delicious form of protein as well.

And if you compost, the fertilizer is free.

I too would like to know the cost per calorie.

I haven’t done the math but I have read that growing duckweed to feed tilapia is a very economical alternative to commercial fish food.

Sounds like it's free for him because he was going to keep fish anyway. The fish aren't a means to an end in his case; instead, the vegetables are a bonus.

Well this site : https://lakewaytilapia.com/Tilapia-Feeding-Guide.php seems to have all of the information you need to understand how much food it takes to generate useful amounts of Tilapia. Could be combined with an aquaponics set up to do the TCO calculation.

Duckweed is a good tilapia feed, but requires a nitrogen source. Use it to supplement azola, it has around 4% more protein.

The problem with tilapia is they reach breeding size long before they reach useful eating size. Upon reaching breeding size, they pretty much quit growing and put all their energy into offspring. They are nearly impossible to separate by sex. Commercial tilipia is treated with large doses of hormones to hermaphrodize the fish to a single sex and grow those nice sized fillets.

Something I've wondered is what sort of distribution can you maintain in a Tilapia population. In some fish populations once you get to a certain size those fish can cannibalize the fry such that you get no additional fish regardless of breeding until they are removed. Any thoughts on that?

That doesn't happen in nature because the small fish can fit into hiding spots the large ones can't. That's why people who own ponds toss in things like pallets and felled trees. That'd be easy to replicate.

Fry are typically separated from the larger fish with netting. Sure, you could keep them all together, but a huge amount of system resources will be consumed by the endless cycle of breeding and cannibalizing and you will won't get fish to a useful size.

Except fertilisers are bad for the environment, especially Nitrogen which is mined.

I have a friend who is building a commercial aquaponic setup and he claims that not only is it better for the environment but it is price competitive now and will be cheaper than hydroponics as the prices of fertilizer keep increasing.

Fertilizers are not bad for the environment. They are bad for our water supply, but fertilizer that doesn't get to the water supply is helpful.

You try and tell that to the people of Nauru.

A substantial fraction of the world's natural gas is burned to produce nitrogen fertilizer. This is largely obtained through fracking. Fertilizers, as they are used on the large scale, are pretty bad for the environment.

You seem to be arguing that the current production of fertilizers is bad - but that doesn't implicate fertilizers in general(unless it is impossible to do otherwise for some reason).

Fertilizers in general aren't necessarily bad. It is important for us to actively recycle our phosphorous and potassium, because there is no short term replenishment of these vital elements in the soil. For more information, I highly recommend "The Humanure Handbook": http://humanurehandbook.com/downloads/Humanure_Handbook_all....

Fertilizers do increase the growth rate of plants. However, there is mounting evidence that nutritional content is inversely proportional with growth rate.

Mined? Its applied commercially as anhydrous ammonia, which is produced from air and electricity.

The vast majority of nitrogen fertilizers are produced by burning natural gas with atmospheric nitrogen to produce NH3, NH3OH and CO2.

https://en.wikipedia.org/wiki/Haber_process

I guess in a way, the natural gas extraction is a mining process.

You don't have to feed the fish - you can also grow black soldier fly larvae and have them automatically feed the fish for you.

https://www.theaquaponicsource.com/blog/black-soldier-fly-la...

Indeed.

Permaculture practitioners have borrowed heavily from provably long-term sustainable aquaponics systems, though these tend to be larger scale (field-sized) and seasonal (wet season you have ponds, dry season you don't).

I haven't seen numbers on effectiveness, but similar to the article you linked, there's fly traps (easy to enter, hard to find their way out) that float on a pond - you put a stinky bit of old meat, cow pat, etc in there, flies lay eggs, fish either eat the larvae that drop through slats, or the flies when they touch the water. Similarly, small solar lights at night near the water's surface to attract more free food.

Geoff Lawton's 80 square metre aquaponics pond here: https://permaculturenews.org/2014/01/25/perfect-permaculture...

small error - Geoff's pond is 800 m^2, not 80(per his linked site). But thank you - this is my first time seeing his material. I've been doing forest gardening for ~12 years on my site, and am thinking about developing a nearby natural depression as a pond - Geoff seems like exactly the kind of person I need to study.

If you need additional input you might also want to check out Sepp Holzer [0].

[0] https://www.youtube.com/watch?v=DFQUKQVwRXU

Ah, fat finger mistake.

Glad you like Geoff - he's a legend in permy circles, and for good reason. Check David Holmgren, Bill Mollison (the two co-founders of permaculture)... and you'll doubtless find lots of other people's work to investigate from there.

Permaculture pushes the idea of building systems that don't need a constant input of external resources... more difficult to design, but maintenance is naturally cheaper / easier, and more resilient.

I raise channel catfish in my own home aquaponics system. If you don't plan on eating the fish or enjoying them as pets, it's not worth it at all.

Feed is indeed the big pain point. All good feeds have fish meal and GMO soybeans etc, and the only way to get a reasonable price point is by buying a 50lb bag from a farm supply store. With a 3 month shelf life, you need a lot of fish and a lot of time dedicated to feeding to not have spoilage.

Theoretically a true closed home system could be achieved by routing household urine to a green tank growing algae, solid waste and food waste to a black soldier fly larvae bin, and feeding the algae and larvae to the fish. The BSFL harvest themselves, and the green tank could be periodically pumped into the fish tank on a timer.

None of it would be terribly complicated to build into a new home, but there's no will to do so as most people would find it gross, preferring to eat artificially cheap fossil fuel fertilized products and have their waste magically disappear.

http://www.backyardaquaponics.com/forum is a tremendous resource.

Do you have an opinion on the "healthiness" of a pure hydroponic system?

Healthfulness of foods by comparative farming practices is not something I have been able to find any solid information about. Hopefully our taste buds know what's good for us when they're not confused by sugar and fat.

Life - Dan Barber said on "Chef's Table" that he felt his produce tasted better and better as he put more life into the soil. The hydro growing medium is relatively sanitized.

Freshness/Ripeness - We had an organic CSA farm box last summer, and in head to head comparisons, the stuff we grew at home (both soil and aqua) tasted way better. I think this is because we picked it when it was ripe and ate it immediately.

I do have some worries about using plastics. unless you are doing a large-scale operation with concrete and / or glass, hydro and aqua both involve water making a lot of contact with plastics. I have to assume that food grade plastics are safe, but no one really knows for sure.

My gut feeling is that as long as you're meeting all the needs of the plant, freshness/ripeness matters more than the presence of other life in the growing medium.

Do you need to buy fish meal, or can you DIY it for cheaper?

I've been wondering about this for a long time. Many articles on the net gloss over the fact that conservation of energy also holds for "closed" aquaponics systems, and that in the end, we eat biologically processed fish food that needs to be bought in the first place. Fish food is probably produced with less stringent rules than food for humans, e.g. regarding heavy metal content \m/ and other contaminations.

I've been thinking about BSFL for aquaponics and there is one problem: warm blooded animal feces should never get into the water. If it could then you wouldn't need fish btw. I don't know how many E. coli bacteria would survive the BSFLs. I guess this could work for your home, but I would not risk that. Of course you can test the water, but no one did that yet as far as I know.

Azolla = free fish food. It obtains both nitrogen and carbon from the air and can double in mass every 2-3 days. Protein content is 17%. Needs only a few inches of water, sunlight and trace minerals.

I've done the math, and while Azolla can't provide 100% of fish nutrition, it can easily provide the majority of it. It can also provide human food and chickens love it. So do pretty much any domesticated animal: many papers have been written about studies on azolla raised hogs, ducks and cows.

Maybe not human food - it may contain a neurotoxin. So not good for long-term consumption. Let the fish/chickens digest it first!

Good to know about the possible neurotoxin. Any suggestions for further information on the topic?

Wikipedia?

Been there, done that and have read dozens of research papers on azolla as livestock feed, but there hadn't been any human research when I delved into the subject. That was quite a few years ago, however. I'll dig back into the stacks and see what I find. My chickens prefer azolla over just about anything, I need to grow more of it.

BMAA is the neurotoxin (implicated in Alzheimers and Parkinsons). It also bioaccumulates over time, and potentially up trophic levels. So definitely not fish wonder food until there's some serious testing done.

Thank you. I will definitely look into this. At the very least, it still makes an effective and fairly high nitrogen organic fertilizer, while drawing down atmospheric CO2. It's so effective at harvesting CO2, ancient azolla sequestered sufficient CO2 (from 3500 ppm down to 650 ppm) to create a global ice age: https://en.wikipedia.org/wiki/Azolla_event

Edit: researchers are still studying the issue, but it seems some plants may be capable of concentrating BMAA, which is highly water soluble. Wheat seems to capture it in proteins of the shoots. I haven't found any further specifics other than cycads, which have a cyanobacteria symbiosis and concentrate it in their seed coatings.

I ran a small home/experimental aquaponics system for over a year, fed the fish, primarily, free worms out of my vermicomposters.

I'm far from an expert but I've seen some interesting things where people replace the fish tank with worm bins and/or black soldier fly bins and they just use compostable material and kitchen scraps as the feed. The flies especially will eat pretty much anything but the worms are easier to keep alive. The plants are fed hydroponically by pumping water through the feed bins, so it soaks up the nutrients in the compost. It's an interesting concept.

As the author, yes I didn't really discuss that. But on the other hand, I would argue I wasn't trying to gloss over it either!

In my case, I took my fish tank which previously existed and turned it into something more -- at the same time, I also dramatically reduced my upkeep time because of the lack of water changes.

> One very cool answer is aquaponics. Aquaponics is a plant growing technique similar to hydroponics, which is basically growing plants in a medium other than dirt with water. The cool thing is this: Where a Hydroponics system requires you to add nutrients to the water to feed your plants (basically fertilizer), an aquaponics system uses all the nitrates produced by your fish as natural fertilizer! What a perfect solution for my laziness – I can stop doing water changes and let plants do the work for me, all the while saving (a bit) of water and always having home-grown produce on hand!

I'm no expert beyond some YouTube research, but apparently plain old hydroponics is way cheaper/simpler/more productive than aquaponics, if the fertilizer aspect doesn't turn you off.

Hydroponics vs Aquaponics: https://www.youtube.com/watch?v=J0fsehjZfzc&

Good educational video on aquaponics: https://www.youtube.com/watch?v=xg2MfC-Oi18

Here is a very nice aquaponics system: https://www.youtube.com/watch?v=wpGwK81tOIs

With aquaponics you do have to “change the water” with aquaponics. From what I’ve read you can’t take the “hot” untreated waste water and feed it directly to plants. There’s a step in between involving another tank.

You typically have a high surface area medium (pea gravel) in the sump or in another tank that provides a bacteria filter for the waste breakdown.

One of the great upsides to Aquaponics is enforced trust.

Since fish are very sensitive to water conditions, you can bet that there will be nothing added to the system that will kill the fish. If it is safe for fish, then it is safe for humans.

This can't be said about Hydroponics or Soil farming. But with Aquaponics, the farmer is forced to play nice.

I have tried aquaponics pretty hard about two years ago. I found the idea super interesting ( and still do).

After a while my plants started decaying over time. Getting black spots, very white. Started having holes in them, ...

After further reading, I learnt that plants need more than just nitrates. They also need manganese, calcium ... A whole bunch of elements you can't get in a closed system (nor in the fish food directly).

I went back to growing outside.

I would definitely recommend aquaponics, but for people that can setup their system outdoors where rain water will bring all those needed additional elements.

rain water is somehow pure and should contain no mineral elements

New farmers tend to disregard the often lengthy process of establishing a well bred fauna of biological filtration similar to a freshwater fish tank. It helps to reduce rot in the roots and nutrient concentration and uptake issues. Similar lessons can be learned in the field of Tilapia farming as a means of a stage of the water treatment system.

Interesting, In my experience of trying to start a home aquaponics startup (and quickly failing) I found that it is very difficult for this to be small scale, i.e., places like growing power, green and gills, farmed here, which have a comercial aspect are more successful. And 2 it is not cost effective at all. While I loved watching the fish, the difficulty with the plants, lights, nutrients, and automation system was a nightmare that was barely rewarding in terms of produce quantity.

If you're interested in this, you might want to check out AutoMicroFarm[0]

[0] https://automicrofarm.com/

Thanks for the shout-out! I had to put the business on pause this year while dealing with family issues. I plan to get back to it in 2018, however.

Edit: Just saw you asking how things have went on Medium. I'll write a blog post / email update about the past year (2017) soon!

Awesome! I'm not in a living situation which would allow me to have an AutoMicroFarm set up, but I've been following the project for a few years and really interested to see how things are going.

I've read about various aquaponics systems in the past.

My main concern would be regarding pathogenic bacteria from the fish getting into the growing plants. Some plants won't have an issue like that, but I was under the impression that other plants like lettuce don't do a good job of filtering microorganisms out of their water supply.

This is related to those news reports about contaminated water and lettuce crops from the past decade.

I used to run home aquaponics for several years, and it was a very healthy environment for the fish and the plants. If anyones interested, here's a short clip of my Perch from a few years ago: https://www.youtube.com/watch?v=_ojePlSxkjs

If anyone is interested in tracking the climate of their farms on their smartphone I'm producing a Temperature and Humidity Sensor & App with Alerts. Some of our customers are Aquaponics Farms and we're working on a Waterproof Temperature Probe that you will be able to place in the water.

Here's more info:

http://www.kokonaut.com http://www.instagram.com/kokonautweathersensors

If you do decide to buy, you can use promo code EARLYADOPTER10 for $10 off

used these in the past with arduino https://www.amazon.com/Gikfun-DS18B20-Temperature-Waterproof...

How would you rate it? I have one of these as well and am planning on using it.

Anyone who wants to grow anything in a tank should read this incredible book: "Ecology of the planted aquarium" by Diana Walstad. If you don't know what aquascaping is about, try googling "Takashi Amano" and just browse through the pictures you find. I'd guarantee you would dream about creating something like that. And that hobby truly is fascinating. However it's for brave tinkerers and tenacious explorers.

For those who are interested, here is more content for the series, including how the grow beds and swirl filter are built:

https://www.thissmarthouse.net/building-a-stylish-home-aquap...

I've been wanting to do something like this for awhile since I already keep fish (as pets) and grow hydroponics separately. Unfortunately living in an apartment there's only so much space and I can't do things like run pipes under the floor.

Fun use of a bell siphon: Pythagoras' Cup. https://www.youtube.com/watch?v=ISfIT3B4y6E

Interesting synergy

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