Backyard Aquaponics
A place to discuss aquaponics

I posted this at my member system page... re-posting it here to seek further expert opinions and feedback.

There were several feedback received in different forums saying that I should re-look at my stocking density and it is more.

Please have a look at our commercial design diagram attached herewith. We are still working on it and would like to make corrections and amendments going forward.

On stocking density, I would like to raise more tilapia going by Ebeling's study (0.25 pounds per gallon/113.5 g/L). Going by that, I should be growing 6242 kg fish in 55kL pond. Assuming an average weight of 400 g per Tilapia, optimum number of fish in the pond is 15000 tilapia.

Could you advice me what is wrong in this design? Currently I have 4000 fish. Can I double or triple the amount of fish? What changes should I make in the system so as to reach the optimum productivity?

I look forward to your thoughts and would really appreciate it.

Can't see the detail on my phone, though with that size system, you would be mad to have only one pump from a reliability point of view.

Which forums did you post on?... couldn't see anything on the 4 usual aquaponics forums??


Which Ebling study/paper are you referring to?.. and what methodology was he referring to/utilising?

15000 tilapia @ 0.4kg.... would represent a biomass of 6000kg...

In 55,000L of water.. 55 cubic metre... that would represent a stocking density... of roughly 110kg/m3

Possible with Tilapia.... and only Tilapia...

But only with direct oxygen injection... and ONLY possible with total solids removal by backwashed screen filter.... and appropriately sized bio-filtration...

And carbon dioxide stripping... considerable daily pH buffering... and high volume water turnover...

And that would be a knife edge... 20 mins away from total disaster operation...

In other words... a full blown, carefully designed RAS operation.... constantly monitored 24/7/365.. and staffed by highly experienced aquaculturalists...

What volume of water can your 0.5hp pump move per hour?

Do I see it correctly that you want to pump around a 55kl pond with a 0.5hp pump? You want to run this "commercial" system with only a 1,000 liter bio filter and the rest grow beds and NFT? For the rest I think it's not going to work at all! Just follow you water distribution and you can easily see why not. It's too much to start about....

I agree with Mattyoga - you would be mad to only have a single pump in a commercial system. In fact, many people with a backyard system have more redundancy than that.

I am also concerned with the amount of fish you want to stock. How much filtration does the system have? This will tell you the stocking level.

Nanniode ... you seem to be taking a bit of published RAS knowledge.. regarding possible maximum stocking densities...

And totally ignoring the other design aspects of such a sophisticated "knife edge" RAS operation...

Tacking a few plants... and/or swirl filter.. onto a stocking density like you currently have...

Just isn't going to cut it in the longer (not to distant) future.. and raising your stocking density further based on your current design...

Would just be fish murder... only mitigated by the fact that the fish would die quicker...

Ah, shoot! I'm not going to react any further on this. Even as a complete noob in AP it's crystal clear to me this can't be a serious proposal for a commercial system. You want to be a consultant for others? Please Nannoo, please get a reality check. Please?

Yep.. I agree.. I really don't think you know what you're doing.... and I don't think you're genuinely interested in anyone's advice...

I'm done...

Please post when you 4000 fish die.... I'm running a sweepstake...

Put me down for within the first week Rupe.

Owah.. that's unkind Arbe...

But if you mean if he were to stock to 15,000 fish...

Then I'd suggest about an hour...

At current stocking.... I went for a month... more informed opinion suggested 2 months.. given the water temps/feed rate are falling...

(or perhaps that should be non-feed rate... )

I'll go for benefit of the doubt, a month! What is the price? A BYAP system?

And if you really want to raise that many fish....

Why not just do low tech pond based aquaculture???

Or full blown RAS?

What's the point of growing 800 plants... just to call it "aquaponics"...

Heck this place is currently running at about the density you want to stock Nanniode...

And is producing over 120,000 plants per month...

At full capacity... at around 100 tonne per year... about 4 million plants annually..

Thanks, everyone! He he... I guessed it right.. we can talk on and on regarding stocking. And, can we arrive at a consensus?

Forums - sorry, I meant different forum pages here at BYAP itself. I do not like other forums because they don't discuss things much.

Thank god my fish 4000 of them are not dead yet and are pretty active and seemingly happy, eat all the 2 kg consistent feed I give and then nibble on the pond walls all the time. Not seen a single fish death in the past 2 months.

Please feel free and and let us try reaching a consensus on stocking and things that need to be changed. I am not working for somebody. This is my own system and I am trying to get things correct and to optimum level of productivity. There is budget constraints but as the fish grew, I can definitely make several changes. So only I sought your view points and value them immensely.

Back to the questions so far.

First, there are plenty of literature available especially from eminent university professors/RS specialists on stocking.
Have a look at one of them here -http://www.aces.edu/dept/fisheries/education/documents/Model_Aquaculture_Recirculation_System_MARS.pdf



Pump - you are right we started with 0.5hp pump throwing out 6000L/hr turning around the water in 9 hours approximately. I agree I will need a bigger pump when fish increases its mass. Currently, it is averaging 75g to 100g each, say roughly 300-400 kg fish in the pond.

Filtration - biofilter+gravel growbed is approximately 40,000L area which we feel is okay for some time. I am looking at water hyacinth's help in filtration too, now growing at 30x2 feet bed and a border wall.

Aeration - 8400L oxygen injection per hour to the bottom of the pond. There are forty 1-1/2" air stones diffusing air at 6 feet bottom.