Backyard Aquaponics

School/Class Project
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Author:  BIG K [ Nov 30th, '08, 06:38 ]
Post subject:  School/Class Project

I am looking at three different designs. What I need is some help with some formulas. Is there an reference page that I can access?

In particular, if I have a 240 gallon fish tank and have the capacity of fish say talapita, what can I expect to grow?
I can see that there most likely is a formula for "X" kind of fish (lbs.?) per gallon right?
likewise it would depend on what plant to how much of each.

I bet that there is even a refernece page for what the reqirement for each plant is?

In the designs that I'm looking at they apeares to be basic and not at "capacity" and I want to utilize what is being produced.

By looking at this disjointed text you can tell that I'm not an educator, just a over envolved parent.


Author:  badflash [ Nov 30th, '08, 10:43 ]
Post subject:  Re: School/Class Project

Aquaponics is in its infancy, so everything is thumb rules right now, not formulas. In general, you need about 2 to 3 times as much growbed as you have fish. This is dynamic as the fish grow and so do the plants.

Tilapia are a great fish. They can tolerate as much as 1 2 pound fish per gallon of water in a tank that size. The problem is they grow, and you need to maintain a balance between the plants and the fish. This drives the need for a large system where the balance between the fish and plants can be maintained as you harvest fish and plants.

Tilapia a super breeders and unless controlled the baby fish will ruin the system.

Author:  RupertofOZ [ Nov 30th, '08, 11:42 ]
Post subject:  Re: School/Class Project

Actually it's more accepted as 9lb/26 gallon.... and at least as much growbed filtration volume as tank volume... ie.. 1:1....

Any higher stocking densities.... and/or as fish grow to maturity (eating size)... requires 2:1 ratio.... :wink:

To get to 12lb/gallon would require a 2:1 ratio for filtration IMO.... and I think 240gallons is just a bit small to be pushing for those sort of densities...

Play it safe to begin... you can always expand/push the boundaries as your knowledge and experience grows... :)

To translate... with a 240 gallon tank.... you need at least 240 gallons of growbed filtration...

At 9lb/26 gallons.... that's about 22-25 (lb of) fish....

Author:  RupertofOZ [ Nov 30th, '08, 11:46 ]
Post subject:  Re: School/Class Project

My bad... (no edit facility).... should read ... 9lb/26gallon.... (our measurements... 3kg/100L)

Which gives you about 70-80 (lb of) fish.... maximum.... and then it depends on what sort of pump/sump setup you go with...

Author:  BIG K [ Nov 30th, '08, 15:13 ]
Post subject:  Re: School/Class Project

Thanks for the responces!
I see there indeed is a learning curve and need to start from the bottom.
When you say I need 1:1 ratio grow bed filtration, in this case 240 gallons worth, what does this translate into for sq/ft?
If I had a growbed(s), how much total?
I guess the depth of the growbed would depend on the plant?

How do you figure out how offten that you cycle the water through?


Author:  RupertofOZ [ Nov 30th, '08, 15:38 ]
Post subject:  Re: School/Class Project

General rule of thumb (for most recirc systems) is the volume of your tank at least once/hour...

Accepted, but not compulsory, depth of growbeds is 12" (30cm)....

Author:  KudaPucat [ Nov 30th, '08, 15:43 ]
Post subject:  Re: School/Class Project

The best depth for a beginner is generally recommended as 30mm minimum, or, as you're from the US, 1ft
240 gallons of ft = 240 gallons of gb
gb at 1' deep,
this means I can't work it out in crazy measurements. so...
approx 900L
300mm deep.
900/300 = 3m²
which for your units is 32 sq.ft.

Author:  KudaPucat [ Nov 30th, '08, 15:46 ]
Post subject:  Re: School/Class Project

damn the no edit button
generally recommended as 30mm minimum

should read 300 as rupe said... sneaky bugger's faster than me.

Author:  BIG K [ Dec 1st, '08, 04:32 ]
Post subject:  Re: School/Class Project

Thanks again for the replies. Being new I'm not sure of the right way to post as this I guess could be posted in the General section.

So what I'm seeing is that I would have 32sg/ft of growbed 12 inches deep? Sorry for the US measurements. I am trying to grasp one idea at at time.

KP: I checked out your system and your containers (fish tanks) look to be the same size as the ones that I may have a line on. Are they 240 gallons or 270?
Is $40 US a good price for one?

I am trying to come up with a design with a limited space to incorporate the growbeds. Any ideas?
Can I stack the growbeds? How far about would I have to space them? Using natural sunlight vs artifical?

About this forum/page: is there a way to review the thread that you are comenting on without using the brousers back button?
is there a spell checker that I'm missing?


Author:  Outbackozzie [ Dec 1st, '08, 04:51 ]
Post subject:  Re: School/Class Project

They are called IBC's (industrial bulk containers), $40 is a pretty good price, even in $US.

Regarding space and design, have a good look through the members systems threads. There are some pretty compact designs. Natural light is the most sustainable way.

There are add-ons for various browsers that spell check while you type.

Author:  BIG K [ Dec 2nd, '08, 23:24 ]
Post subject:  Re: School/Class Project

Outbackozzie: The reason I asked about the Forun's functions is that I belong to another Forum that has those available. Just wondering if I missed them. I just found the topic review area at the bottom. Last time I checked there was not a slider bar to check the whole thread.

Is there a program available online or freeware that you are using to diagram and show other members plans for their systems?
Can you point me in the right direction?

When you are using an ebb and flow system (H2O goes to a tank to flush into the grow tray(s) on a timed basis?). Is there the same or close to the same amount of H2O being transported back into the fish tank?

Thanks again!

Author:  RupertofOZ [ Dec 3rd, '08, 10:06 ]
Post subject:  Re: School/Class Project

Essentially yes... the only water lost to an AP system is through transpiration from the plants... typically about 10-15%/week....

How much water returns to your tank (at any point of time) depends on whether or not you use a sump, chift pist etc....

Author:  earthbound [ Dec 3rd, '08, 11:08 ]
Post subject:  Re: School/Class Project

BIG K wrote:

Is there a program available online or freeware that you are using to diagram and show other members plans for their systems?
Can you point me in the right direction?

Sure is.... Google sketchup is a great tool, you can download it from here:

People have posted up some of their components used in systems and system designs here: viewtopic.php?f=9&t=4101

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