Backyard Aquaponics
A place to discuss aquaponics

I recently met with a professor that is researching aquaponics at the local university. Our conversation blew my mind. He developed a super simple design that has research to back up its success. Instead of the lay person like me stumbling in the dark, he did the research and experimentation to develop a system that is cheap, viable, and well, extremely simple and more productive than I ever imagined.

It uses a 4x8 plywood sheet with 2x4 walls that is lined for the GB. styrafoam is then floated on top of the water with 48 holes drilled in and the plants are grown there. NO GB MEDIA. It uses a 100 gallon pond which as a very small (3 gallon) mesh tubing filled with biofilter material as the only biofilteration in the whole system. The pond is heavily aerated.

The water is transferred to the GB MANUALLY. 5 gallons once a day. When the water is poured into the GB it overflows back into the pond.

The productivity is crazy. 48 heads of lettuce in 5-6 weeks.

What blew my mind was the small biofilter needed. I kept coming back to that in our discussion. his simple answer was "it works, nothing else matters."

This meeting changed everything for me. Making rethink all that I know about AP.

I think the professor was amused by my internal struggle. He said people have come up with all kinds or systems, all without any methodical research or experimentation, some very complicated and have limited to good success. His model is cheap, simple, and highly productive.

I still cannot get my mind around the biofiltration.

Oh and get this, his system has a 70% efficiency rate. Meaning 70% of fish feed mass is transferred to the plants and fish. !!!!!!??!?!?!???!!

Interesting post. Leads me to more questions.

What stocking density did the prof recommend?

What species fish did he use? I would guess Tilapia.

What fish food source?

If your going to aerate heavily, why not just pump and save yourself the headache? You are using power anyway.

I don't see much advancement in the profs ideas personally.

He is talking about feed efficiency rate, I think. To me that doesn't sound so great. I get 50% feed efficiency growing catfish in ponds. I bet it would be higher if I could weigh the algae. I would think a lot of Joel's systems do that well or better. Now he would impress me with 100% feed efficiency.

Are his findings published anywhere?

Thanks for sharing it is an interesting concept.

He uses tilapia. His focus is more on the lettuce than the fish.
He uses cheap trout feed.
He uses about 3 kg of fish in a 100 gal system. After 5-6 weeks the fish double in size.
One 4x8 tray yields 48 heads of lettuce every 5 weeks.
His 30 yard by 30 yard farm made $300,000 bucks last year.

I gather the biofilter is in the pond and it requires massive air pumping for circulation as well as air.Why on earth would you want to do that.? If you are expending so much energy on pumping air you might as well pump water.
Honestly most backyard systems want to grow much more than lettuce. Has he done research on the effectiveness of his system for growing other plant types? Many people have observed the beneficial effects of earth worms in matured systems has he tested how well his system works for worms, has he tested how well his system performs compared to a mature system that has worms?

His research maybe of interest to some commercial applications but for backyard setups I personally tend to have more faith in the results of real working systems than in academic theories about what is best.
Is that turnover or profit?

He has a 50W air pump for 3-100 gallon tanks. He is going to start using pumps but hasn;t yet because it works and keeps things VERY simple.

I don't understand your last statement about real working systems novaris. He has utilized both academic theory AND proved that it works through a real working system.

I'm pretty sure his answer to the worm question would be "why would the system need them? The system works fine without." Anyway there's no media for the worms to live in.

He plans to grow other vegetables. he wanted to perfect lettuce first. Can't question his logic.

Novaris, I had the same feelings. I kept asking him about other systems and what not but he kept saying "that might work but why would you want to do that? my system is simpler and more productive." He did have a point which I could not argue.

it was net gain.

Curious how argumentive people are to this thread. Interesting...

$3700 per sq mtr
Hard to imagine

Nothing wrong with a healthy bit of skepticism... I've read about all sorts of aquaponic claims over the years, some of them are good, others not so... Did you see his systems?

3kg of fish in a 100 gall system that double there size in 6 weeks that i would like to see

4x8... I assume you are talking "feet" .... so, 32sq ft.... for 48 lettuce every 5 weeks...

That's only about the same as hydroponic levels of production...

Here's my 20x6ft (6mx2m)... 120sq ft hydro.... doing 200 lettuce in 4-5 weeks...



With a 35w pump... and almost zero labour time... except for ... planting and harvesting...

That's about 8 crops per table... each year... or 1600 lettuce...

30x30 sq yards = 8100 sq ft .... or 752 sq mtr... 1 hydro table (as above) takes up 12sq mtr...

So in that area...752/12 = 62 tables (approx).... @ 200 holes/table...

=> 12400 available holes for lettuce... multiplied by 8 crops per year... => 99200 lettuce per year...


Wholsale rate of a lettuce...let's be generous and say $1/head...
for an annual turnover of $100,000 per annum.... without any deductions for overheads...

Sorry I think he's pulling your leg...

A minimum sized small, highly efficient, hydroponic farm would be about 4 times that size... 250 tables (6mx2m)... or more standarly... 120 12x2m tables... to make around $100,000 per year

And fish doubling their weight every six weeks... even trout and Barra can't do that... and I don't believe Tilapia can either...

And assuming even a 1:1 FCR... the feed bill per year would be a significant proportion of any profit from the sale of lettuce...

If I could get an FCR of 1:1... with a 100% weight gain every 6 weeks... I wouldn't be bothered using my 30x30 sq yd for growing lettuce for $1/head...

Just a quick one what neutrient are you uesing in your hydro

Actually... thinking about it... if we take trout @ 100gms... and a six month grow out to 800gms..

That's a 8x weight gain in 24 weeks... so possible.... and trout are a "premium priced fish... not sure what price Tilapia attract...

But if we assume an FCR of 1:1 ... and harvest at 500-600gms... then that's 50-60gms of feed ... per fish/day... and 60 fish/100L (at harvest size)....

A total daily feed rate of 400-480gms (0.5kg) of feed to be processed by bio-filtration/day..

With the filter quoted...

I'd ceertainly like more details of the filter arrangement... and a contact number of the prof...

Sometimes..."Select" hydro nutrient...

Mostly pre-filtered AP water, 2-3% seawater, occasional urea, chelated iron, EcoRose and Maxicrop...

Thanks where do you get the occasional urea,

Well I seem to have a good growth rate for trout.
But this season the trout were delivered in May so 6 months growth so far, also not sure if the biggest
trout were captured this morning but the biggest was 465g...
Less 50-80grams per fingerling so barely 480% in 6 months.

Bunnings...