Closed Loop Aquaponics

I'm trying to move as close to off grid as possible and I'm considering aquaponics as a way to provide fish for us since I don't have a good place for a pond. Since I'm mainly interested in the fish as I have other areas of my property for growing, all the plants the fish help grow could be fed to the fish in return. If there was surplus leftover for us, that would be great, but not necessary.

My main questions:

1. How viable is aquaponics as a closed loop system? I've heard of growing insects, plants etc. for the fish, but is this truly enough to account for 100% of the food the fish would require? Is it sustainable year around? Can I raise some fish as food for other fish?

2. I'd like as least input as possible, so heating the water would be off the table for me. I live near the Dallas area, so I'm curious what fish I could consider using in my area?

3. If done on small scale, could pumps be avoided? I mean once or twice a day go manually scoop out the water from the fish tank and feed the plants. Or any other idea to avoid electric pumps?

4. I'm interested in how many fish could be raised in a certain sized area, sustainably. I'm also interested in learning about how many fish can be produced for meat by a said number of fish. I have no idea about how many babies a fish has and how many times per year etc. and if that is effected by keeping fish in this rather unnatural condition. Can someone explain to me or point me in the right direction of getting such information.

Thanks in advance

Check out channel catfish and tilapia on Google. Both are raised commercially in Louisiana. Read through the multitude of threads here and notice that most catastrophic failures have to do with equipment malfunction, oxygen crash or lethal nutrient loads.

Carp! That is what I will be using on my set-up. There is a good thread on using carp here on the forums.
Unlike tilapia they are not sensative to tempature .
They are boney....

I'm no expert, but I volunteered a summer at the New Alchemy Institute in Cape Cod way back when. They had aquaponics with fish, and it seemed like the kind of closed loop you're talking about would have been possible.

They had about 10 fish tanks in a big solar greenhouse. The tanks stood about 5 feet tall and 3 feet dia, made of a kind of translucent fiberglass that was called calwal (sp?). They had one tank up a little higher than all the others, into which fresh water would run and sit there getting to the same temperature as the rest of the tanks to prevent the fish getting temperature shock when fresh water is added, and it would also offgas the chlorine from the town supply. The fish tanks got almost black with dark green algae because of the sun on the translucent tanks. We'd siphon some of the dark skanky water down from the fish tanks onto the garden beds, then siphon some of the fresh (but same-temp) water into the fish tanks. There was a bubbler with a nylon stocking for a filter in each tank, and the stocking would fill up with fish shit (in any case, something thicker and smellier than the rest of the water) which we also would put onto the garden beds.

Some of the tanks had a mesh tray in the top and some hydroponic plants growing on top, utilizing the nutrient rich water. The whole greenhouse was extremely lush, and I am sure that photosynthesis was making a great net gain in plant and fish matter.

What I recall (could be wrong) was that the tilapia were mainly algae eaters, and the catfish were bottom feeders. We threw weeds and scraps into the tanks, but I'm sorry, I forget whether we added any other kind of feed as well. I kind of feel the tilapia were living solely on the algae, but I don't honestly remember. I think they said that ideally they'd have a mini-ecosystem with three species of fish, but at that time there were only tilapia and catfish.

I cooked a dozen of the tilapia for everyone for lunch one day.

It is Kalwall. They have lots of stuff for passive solar, greenhouses, etc. Here is their consumer website: http://www.solar-components.com/

They also are the ones that make the white energy efficient skylights--R-20 and 20% light transmission.

I have played with the idea, I am pretty sure you can get to nearly zero input if you have a lower stocking density in the right climate. Feed the fish plant scraps, grow duckweed, and use black soldier fly larvae.

There is a thread here about LEAP Low Energy Aquaponics that goes into some of the power issues.

It is still a tough thing to keep in balance, though.

I think it's probably a lot easier to keep things in balanced if you keep your stocking density much lower than the optimum, and keep adding modest amounts of fresh water and removing dirty water. I think a bubbler might be almost necessary.

The concept you're suggesting is not actually aquaponics, but recirculating aquaculture.

Two books on aquaculture that set the standard are Freshwater Aquaculture by William McLarney and Small Scale Aquaculture by Steven VanGorder. There are no books written yet on permaculture and aquacuture together, though it's a natural fit if you do it right.

The most productive plant in the world is duckweed, and it grows floating in water. You can create a duckweed pond across a berm from your fish pond. If you pumped the water back and forth the duckweed would absorb a fair amount of the nitrates. If you ran that pump through a tank full of gravel you would take care of the nitrification process. Then you could feed the duckweed to your fish, especially if you raise a hervibore or omnivore fish. That can handle maybe 25% of their diet.

You could get more from a black soldier fly larvae harvester to handle all your compost. That might bring you up to 50%.

For the rest you would have to either raise fathead minnows or something similar, or buy commercial fish feed.

Yes, you would probably have to aerate unless you were satisfied with very low stocking density or had a spring.

Hey Tom, I've been working with aquaponics for a few years now, also trying to close the loop. The main consideration with an aquaponic system as opposed to recirculating aquaculture is the presence of the biofilter aka the plant growing beds. These grow beds contain the bacteria that carry out nitrification and allow the plants to absorb the excess nitrogen not consumed by the fish. The removal of this nitrogen is essential to maintaing non-toxic water quality and of course helping to close the loop by utilizing the nutrients not absorbed into the fish (pooped out). I've been growing BSFL on city food wastes with some good success. I'll be writing a thesis this year on growing tilapia with BSFL, duckweed, and algae as 100% of the feed, so I can let you know how that goes!

Avoiding pumps is difficult. You want to recirculate your water once an hour if your @ maximum stocking density, this is to keep the water fresh and oxygenated. Most people opt to not run stocking densities this high because of lots of other problems but I want to illustrate the point that chaining water by hand is infeasible.

Check out Nate Storey's youtube page. He releases tons short videos on aquaponics: https://www.youtube.com/user/NateStorey1. Also check out backyard aquaponics @ http://www.backyardaquaponics.com . As J. Robinson said Aquaculture by McLarney is a a good one for general aquaculture info.

All in all, I will say if you can have a pond and use the ancient chinese pond fertilization method with several feeding levels of fish (top feeders, middle feeders, bottom feeders) it will be 100x easier to maintain and probably yield more too. You can read about that technique in Aquaculture by McLarney as well or Farmers of 40 Centuries.

Hi. I have several years of experience with AP and here is are my answers to your questions based on my personal knowledge:

As was already mentioned in this thread, AP is about raising fish with plants....the plants are part of the package. Otherwise, you are doing a different style of aquaculture. Also, with aquaponics, the plants are generally the main focus (in my experience). Some people are more interested in the fish side, but the bottom line is that you will produce far more plant material with AP than you will produce fish.

1.) A true and fully closed loop system is extremely difficult. Starting to close that loop and providing a large majority of what the system needs without outside resources is possible, but you have to have quite a bit of infrastructure set up. True, you can grow duckweed, BSFL, algae, etc., but it is really hard to provide 100% of your fish food on site and still have the fish be eating a healthy diet. You could raise fish to feed to other fish, but that gets even trickier. You have to have more fish tanks...what do you feed the "feeder" fish...etc. At that point, you are moving more toward fish farming similar to the way it is done today. The embodied energy of raising fish to feed to other fish doesn't pan out, in my opinion. You also have the consideration of topping off your system with water...be it rain water, well water, or municipal water. AP is indeed sustainable year round, depending on how you have your system set up and where it is located on your property.

2.) The fish choice is always a fun one. With no supplemental heating, you would want to just do a bit of research on fish that can handle low and high temperatures, since it will get pretty cold and quite hot in the Dallas area at different times of the year. If you have your system in a hoop house, you will have more control over trying to keep the water warm enough. I live in Corpus Christi, had a system in a greenhouse, and still had trouble keeping Tilapia happy this past winter. I would consider catfish or maybe hybrid bluegill. Or do some searching around. You just have to find a fish that is hardy for temp. swings.

3.) I don't think that you will be able to get around using pumps. The fish need oxygen and the water needs to be circulated in order to clean the water for the fish. You could use less energy by utilizing gravity, small pumps, air lifts, or pumps hooked up to PV cells. As mentioned previously, hand changing water is not practical...especially if you are trying to grow enough fish to eat on a regular basis.

4.) The great and ever-present "it depends." The more fish you raise, the more energy you will need to raise those fish. You can have crazy high stocking densities of fish if you have enough oxygen in the water, but that doesn't mean that the fish are happy and healthy. The general number that I learned for AP is 1 fish for every 2 gallons of fish tank water. ***That is a VERY GENERAL number, though. You can go higher or lower, depending on several factors.**** Helping the fish to breed and self-propagate is a completely separate and detailed topic. Depending on the fish species it is definitely possible that they could breed and raise babies without any additional support on your part, but it is not a guarantee. Sometimes the fish need certain spawning conditions, the babies need protection from cannibalizing, etc. If you have multiple tanks with different ages of fish in them, similar to Dr. James Rakocy, it might really help with the rearing process.

The fish take a while to grow and you need to clean the water in some way, so I think it is worth putting forth the effort to grow awesome plants if you are going the AP route.

This is a complex subject that is worth learning more about. At the same time, it is a relatively young field and people are still learning the ins and outs of what is possible with aquaponics. There are many different facets of manufactured systems like this and even more opinions on what to do to be successful. It will be difficult to set things up in a way where you do not make sacrifices in one area or another. In my opinion, it is almost too much work to do aquaponics at all vs. properly managed aquaculture systems paired with properly managed soil based ecosystems...let alone doing aquaponics right in a closed loop fashion, but I do know that there are some individuals out there that are doing a bang up job of closing the loop and having quite a bit of success. So keep asking questions and keep searching/researching! Good luck!!

A possible approach to pumping some of the water without electricity is to use wind power. Not everything has to run off an electric motor. No, the wind driven pump isn't going to be constant, but in conjunction with an electric pump, you could definitely get the pumping done with less electricity than if you took the wind powered pump out of the system...

Not even Earth is a closed loop system, it is entirely dependent upon solar energy for maintaining life.  I am pretty sure that it is possible to do an aquaponic system that does not require bought in feed - assuming you have a property of sufficient size with sufficient resources...and there is the rub - what comprises sufficient resources and sufficient size?

Say you use BSF for feed for your fish. Have to feed the BSF, where does that come from? Need bins for the BSF - What size and how many to produce, year round, enough to feed your fish? Not going to be an apartment size set up.

Maybe run vermicomposting as well as the BSF and feed worms to the fish too - but same questions, where does the worm food come from? How much space do you need to commit to worm bins?

You will have to aerate and circulate water and you have to have holding capacity for the water.  How much water? Holding capacity, counting fish tanks, sump, hydroponic beds - how much space for handling the water?

I just built an aquaponics system in an off grid restaurant at the edge of Amsterdam this Summer. We used airlifts to move the water. We have two IBC's for the fish so about a little more than 300 gallons because they are not full. We are using two air pumps one at 20 watts and another at 10 watts. The flow is about an exchange per hour maybe a little more. We also have bubblers in  the corners of the tanks to prevent dead zones and move things to the lifts to get to the filters. We are experimenting with living filters, three types of mussels. System is running fine and gets filled with rain water when needed. I like to always have at least two pumps in case one fails. In this case both are air but one moves water and oxygenates while the other agitates water and oxygenates. The system is level with a airlift in each tank and bed. If you had more power for 20 watts equivalent per lift you could lift an inch or 1/2 inch per lift and then gravity feed back to start. That was the original concept but we realized it would take 120 watts for our setup so we went with level.

If I had to do it over and we may move the system soon, I'd put in a 30/40 watt and a 10 so I could get two exchanges per hour.

As for closing the loop, in another system we are building down the road it will be an outdoor system and we are planning black solder fly, worms and algae from restaurant waste because none of us like fish food that contains wild fish meal. For now we have an algae harvester.

The outdoor system will eventually have a windmill to move the water-- it is Holland after all

Jason