Small Scale AP system optimization

5 posts in this topic

I've been reading some of the documents found in the downloads section, and I've run into a problem: One of the documents FAO Small Scale Aquaponics Production states that a good rule of thumb is:


40–50 g of fish feed per square metre per day for leafy greens and 50–80 g of fish feed per square metre per day for fruiting vegetables

This is a problem at the 50 gallon scale. A slightly overstocked 50 gallon ornamental aquarium will hold, say, 30 Zebra Danio and 5 Cory Cats. If my research is correct, that equates to about 127 milligrams of food per day. Well, according to the conversion factor found in the document, that gives us approximately 0.003175 M. That equates to roughly 0.03417 Ft2  of growing area (how's that for nano aquaponics!?) This can't possibly be correct, there are videos all over youtube of people with simple top mounted grow beds over 20 gallon tanks with one or two beta in them. They've got easily 10 times (or more) growing area than what those numbers say it should be, yet they are having success.

Furthermore, the FAO document says that when using a media bed, I would want around a 1/1 ratio between biofilter volume and tank volume for a beginners setup (and goes on to state that experienced people can probably double the amount of grow bed area). So now I have a contradiction, I can only feed .034 Ftworth of plants, but I need 50 gallons of volume for filtration? Seems like I get one lettuce plant out of the deal here.

What am I missing? How much grow area would you expect out of a 50 gallon aquarium with roughly 30 zebrafish and 5 cory cats? Can a 50 gallon tank hold more fish than I'm giving it?

Edited by superstewie (see edit history)
NilliamSuby likes this

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Hi again superstewie

I have no knowledge on zebrafish nor corycats, but no mater specie of choice "less is more" never overload is a good rule.

It takes me forever to go back/forth with metric vs US gallon/feet etc. so as an alternative to try answer your Q's

May I suggest you use these calculators/factsheets here 

by Wilson Lennard, they should all be right and tested. They come in both metric and US measures 



NilliamSuby likes this

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SuperStewie....your questions about feeding rates lack context.  When you talk about aquaponics, what particular variant were you thinking of...raft, media or NFT.  What size fish?  What type of feed?  What does 'filtratration' mean?  The FAO manual has regrettably bought into the silly idea of the basic flood and drain system which relies on the media to perform the mechanical and biological filtration functions.

Tiny systems are skewed in terms of the operating regimes that apply to them.  Nothing in the way of prescriptions or guidelines that allegedly apply to larger systems will be of much use below a certain size..

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Hi Super Stewie,

I think you are overcomplicate this stage in your adventure... I have a suggestion....Why don't you read up on the principles of filtration in the first instance and get your head around that?..There are plenty of posts here on this forum which will help you...Just use the search function...I learnt a fair bit about filtration reading and communicating with Gary and Paul on Gary's mega bin system thread and building on my knowledge... Gary floats in from time to time now so he's around to help... Paul has moved on...There are other people around who I think will chime in if you ask...

Once you get a solid grounding then get into the calculations if you wish to go down that path...iAVs uses a particular sand for it's media and Mark McMurtry has also moved on but he has given us reams of technical information if you wish to go that way...

The good thing about aquaponics is it can be as involved as you want it to be...But...I would recommend getting your head around the basics first before upping the ante...

So yeah I agree with Gary, Sort out in your head which way you want to go by answering those and a few more questions then learn the basic and off you go...

I look forward to seeing what you build in the future..Please start a thread in the build section and keep us posted...

We are here if you need...

Good luck



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If you want my recommendation for a small demonstration system, I'd suggest that you consider the Integrated Aqua-Vegetable System (iAVs)...for the following reasons:

  • The design embodies the most cost-effective mechanical and biological filtration to be found in any of the aquaponics variants...very useful for a system that is going to be of compact size.
  • iAVs will grow the widest variety of crops of all aquaponics variants.
  • iAVs is the most productive, resilient and sustainable of all of the aquaponics variants.

You can read more about the iAVs method on


Edited by GaryD (see edit history)
NilliamSuby likes this

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