Aquaponics

I'm a new NANFA member and responses to my introduction encouraged me to describe my aquaponic greenhouse in more detail so I began this thread to do so. Please ask questions or share ideas for improvement. There's plenty of room for that.

I've been an organic farmer for over 30 years and an aquarist for over 50 and was always looking for ways to combine these two passions. Back in the mid-90s I organized a workshop on Integrated Greenhouses and one of the presentors was Dr Mark McMurtry who was doing his doctoral dissertation at N.C. State on Integrated Aqua-Vegiculture Systems (IAVS). He raised tilapia and various vegetables together in a system designed primarily for use in developing countries with protein and water shortages. His design is relatively low-tech compared to other aquaculture and aquaponic systems and, being a recirculating system, it uses water very efficiently. Only water lost to evaporation is needed once the system is operational. Since the Ozarks where I live has been called "top-of-the-line third world" I decided to give it a try and in 1997 I completed construction of a 20' x 12' passive solar greenhouse attached to my home. It was intended to be an experimental prototype to test the concept for possible expansion to commercial scale.

Design: The entire floor and fish vat are formed of concrete with an epoxy coating. The vat is 20' x 4' wide x 3' deep and is recessed into the floor and covered by a slatted wood (black locust) walkway. This way, valuable floor space is devoted more to plant production. Adjacent to the walkway is an 8' x 20' x 1' deep gravel bed for plant production. The floor beneath the gravel is sloped so that water percolates through the gravel and flows back into the vat. The bottom of the vat is vee-shaped so that fish waste accumulates in the vee. 4 small submersible pumps activate 4 times a day on a timer and pump fish waste and water from the bottom of the vat to the surface of the gravel bed. Solids stay on the surface, water percolates down and returns to the vat. Bacteria in the gravel reduce ammonia to nitrite and nitrate and plants absorb the nitrate. Fish feed is the sole nutrient input. I feed the fish, the fish feed the plants, and the fish and plants feed me. i'm growing hybrid bluegill now but have also worked with tilapia and am exploring sturgeon and paddlefish.

It's a very elegant, stable and self-sustaining system. I also have worms growing in the gravel which provide supplemental feed for the fish. Microscopic examination of moss and biofilm growing in the system reveals lots of amphipods, rotifers, daphnia, etc.

Unfortunately, my photos of construction were pre-digital but I will dig around for them and my slide scanner and if possible post photos. I tried to upload some recent shots but need to resize them first. More to come.

Seize the carp!

Gordon

I'm going to read this again when I wake up. Sounds interesting. Would love some pics

That sounds awesome. I agree, I'd also love to see some pictures. No pressure or anything.
I believe AZ9 was contemplating some type of aquaponics set up. I know he'll be interested in this too.
Thanks very much for sharing about this.

Steve.

Here are a few quickie photos. I don't think they are posted in the order I chose but maybe they will make sense.

The photo with bare gravel is being prepped for planting. I "terraform" the surface by dragging a shaped board along a pair of 2 x 4s. This creates a ridge-and-furrow surface with a slight slope. Most plants are planted onto the ridges to keep stems out of the water during a flood cycle. Some, such as chives, watercress, etc are water tolerant and are planted in the furrows. Some I plant in pots which are set in the furrows. One end of the growbed is not terraformed but is relatively flat and I plant citrus and other perennials there. You'll see in this photo that I also have birds. And that's my sturgeon tank and the corner of my native tank.n i think of this as my own little rainforest!

The photo with plants growing is about 45 days later and shows red mustard to the right. The rows to the left are actually weeds from a lettuce crop failure (old seed) which I am replanting today. You can see the water, drawn from the bottom of the fish vat, flowing into the furrows. The pumps run about 15 minutes 4 times a day but cycles are variable according to fish stocking rates, feeding rates, plant growth stage, etc.

The other photo shows the slatted walkway under which is the fish vat. To the right of the walkway is a concrete block retaining wall and behind that is the gravel bed. The retaining wall is raised a couple of inches above the floor and return water flows beneath it and is aerated as it falls back into the vat. I also provide additional aeration in the vat, depending on stocking rates. In this photo you can also see my 125 gal. native tank and the very corner of my 250 gal sturgeon tank.

I have tried a wide variety of crops including tomatoes, melons, cukes, peas and beans, lettuces and greens, herbs, citrus, papaya, and tropical ornamentals. What I have found works best for me are leafy greens (lettuces, spinach, mustard, oriental greens, etc) and cherry tomatoes. Heavy feeders are more problematic and require a high fish stocking rate which I have tried but it requires much more attention and allows much less room for error. After several such errors, I have settled (for now) on my current relatively low stocking levels which are much more forgiving.

I have also tried a variety of aquatic species. I built the system with a radiant heating system embedded in the concrete to maintain tropical temps and raised tilapia, but that's another story. I've also tried pacu, oscars (actually quite tasty), Australian red claw crayfish, frogs, etc, etc, etc. I soon realized that heating costs were prohibitive and switched to a temperate system and now grow hybrid bluegill but I'm always looking at new opportunities and am currently exploring ways that sturgeon and paddlefish might fit.

More later.

Gordon

While I'm posting photos, here are a couple of my sturgeon. The one on the bottom of the tank is a sterlet and the other a diamond. NANFA's captive care page on sturgeon got it right- they are as endearing as puppies.

Wow. That would be a lot of fun to tinker with. How did you get weeds? Isn't it a closed system, with the only seeds being the ones that you add?

Probably from transplanting outdoor crops into the greenhouse. I sometimes lift and bring in tomatoes, chives, herbs, etc before first frost. Also maybe potted tropical ornamentals that are left outside during the summer. Also birdseed. Most of it is chickweed which I made the mistake of allowing to go to seed before removing. Now it's a PITA.

Most of it is chickweed which I made the mistake of allowing to go to seed before removing. Now it's a PITA.

What you need is a chicken!

But seriously... it's a beautiful setup.

Real nice looking set up.
How many hybrid bluegill does it actually take to support a light plant load in your system?

And oh yes, Beautiful sturgeon.

Thanks for sharing.

Steve.

Steve,

The beauty of this system is its flexibility. Right now I have a light fish load with about 100 bluegill, mostly mature, although it's been a while since I've taken inventory. One of the weaknesses of this system is that it's difficult to observe the fish. Initially I used my 125 gal. tank as an observatory. Water from the vat would flow through it during pump cycles and i kept a few bluegill, and later goldfish in it on the theory that if problems occurred in the vat it would show up in the tank, sort of like the canary in the coal mine. But bluegills are so bulletproof that it proved unnecessary and now it's my native tank. I'll try to capture a couple of bluegills for a photo op. Current bioload is enough to support a crop of greens and a few tomato plants. This spring I will increase the population by adding a couple of hundred 2-3" fingerlings. I buy hybrid bluegill from the fish trucks that come monthly to local feed stores during pond stocking season.

Real nice looking set up.
How many hybrid bluegill does it actually take to support a light plant load in your system?

And oh yes, Beautiful sturgeon.

Thanks for sharing.

Steve.

Very nice setup, I love it

You might find this thread interesting.
http://forum.nanfa.o...__fromsearch__1
It is about raising black soldierfly larvae and has some information about building a self harvesting composter that seems like it could easily be incorporated into your system. A little more free food for your fish.

Interesting. I'll have to give it a thorough read.

I have had some experience with soldier flies, albeit unintended. For a while I tried worm farming on a small scale in my greenhouse (Can 'O Worms) and more than once had my culture taken over by soldier flies. The problem was that my greenhouse is attached to my house, to my kitchen in particular, and when they began to show up uninvited for dinner my wife said "Enough!". I'm not sure I could convince her to intentionally grow them.

At one point I released some red wigglers in my gravel bed and it's now pretty well populated. During flood cycles I can sometimes see babies getting flushed into the fish vat. When I harvest fish I just dig in the gravel for a worm, put it on a hook and ...Bam! Like fishin' in a bucket.

You might find this thread interesting.
http://forum.nanfa.o...__fromsearch__1
It is about raising black soldierfly larvae and has some information about building a self harvesting composter that seems like it could easily be incorporated into your system. A little more free food for your fish.

Very nice system, I am planning similar, in a free standing hoop house, with Blue Gills and maybe a few Yellow Perch.

Right now I am looking at a 24' L by 16' wide hoop house. Using some stock tanks, several 300 gals and a couple 150-175gal ones.