How to size my aquaponics?

[Orlando Collu]

Dear Friends,

I am new to aquaponics, I live in Sardinia, Italy. I just bought the book aquaponic gardening and I was trying to use the rule of sizing the grow beds to the fish tank.  If 0.5 kg fish go with .1 square meter grow bed and 25 liter tank,

then 500 kg fish go with 40 square meter grow bed and 10.000 liter tank...........?  

But in some videos of UVI system I see huge deep water grow beds compared with the fish tanks, that seem to apply some other calculation. Can anyone tell me what is the explanation?

[George]

I believe the explanation is UVI is not a media system such as the one you've read about in the Bernstein book.  You shouldn't compare the two with respect to sizing ratios. 

UVI, I think, removes solids from the system, whereas solids stay in a media system (mineralized in the beds)

[Jonathan Kadish NYC AA Chair]

Orlando,

You really should say just what you want to do with your system. Are you growing for yourself, your family or your community? Is fish a primary product or do you just want to grow vegetables? Large systems can be very different from small systems.

[Orlando Collu]

Hello Jonathan,

Fish is not a primary product. My idea is to grow vegetables for a small community of 50 families. I was thinking of combining approx 20 square meter media grow bed to mineralize and remove solids from the system and 60 - 100 square meter deep water culture connected to a 10000 liter tank.

Any suggestions?

[Jonathan Kadish NYC AA Chair]

What you are describing is a hybrid system and will work.  A farm called Green Acres in Florida has just such a farm. http://www.greenacreaquaponics.com They also offer training that can show you all you need to know. I know it is a trek from Italy but winter is coming and Florida has nice weather in the winter.

[R.K. Castillo]

Hey Orlando,  

I'm not an expert but I found these calculations on the forum in the DWC group.  They said:

the rule of thumb for raft systems that I use is minimum of .3 pounds of fish for every square foot of raft space and at least 4 gallons of water for each pound of fish. That works out to 10 pounds of fish for every 4'x8' sheet of foam. If your fish load gets above .4lbs/sqft then you need to add solids filtration to keep poo off roots of the plants.

I would recommend going from your fish tank directly to your media bed as your solids and bio filter and a place to grow some other plants that wouldn't do well in a raft.  

Then from your media bed have a bell siphon that goes to DWC troughs and then back to fish tank.  

[Orlando Collu]

Ok, Thanks.

R.K. Castillo said:

Hey Orlando,  

I'm not an expert but I found these calculations on the forum in the DWC group.  They said:

the rule of thumb for raft systems that I use is minimum of .3 pounds of fish for every square foot of raft space and at least 4 gallons of water for each pound of fish. That works out to 10 pounds of fish for every 4'x8' sheet of foam. If your fish load gets above .4lbs/sqft then you need to add solids filtration to keep poo off roots of the plants.

I would recommend going from your fish tank directly to your media bed as your solids and bio filter and a place to grow some other plants that wouldn't do well in a raft.  

Then from your media bed have a bell siphon that goes to DWC troughs and then back to fish tank.  

[Jonathan Kadish NYC AA Chair]

For DWC or any Aquaponics system, it is not the number of fish but the quantity of food introduced into a system. In a Rakocy type DWC system feed rates are 60-100g per square meter of raft. You would then calculate your fish load based on the food available. For a hybrid system you only need 10-20g per square meter per day. In a DWC system solids are removed where as in a hybrid system they would remain in the grow beds making the need for fish waste greatly reduced.

R.K. Castillo said:

Hey Orlando,  

I'm not an expert but I found these calculations on the forum in the DWC group.  They said:

the rule of thumb for raft systems that I use is minimum of .3 pounds of fish for every square foot of raft space and at least 4 gallons of water for each pound of fish. That works out to 10 pounds of fish for every 4'x8' sheet of foam. If your fish load gets above .4lbs/sqft then you need to add solids filtration to keep poo off roots of the plants.

I would recommend going from your fish tank directly to your media bed as your solids and bio filter and a place to grow some other plants that wouldn't do well in a raft.  

Then from your media bed have a bell siphon that goes to DWC troughs and then back to fish tank.  

[Orlando Collu]

Hey Jonathan,

Thanks for the data!  I was actually looking at a video from greenaquaponic and I saw huge grow beds DWC and two side beds with media, There were not huge tanks there, so I wondered how the system would work.

Now with this hybrid system 10-20 g per square meter, makes sense.

[Orlando Collu]

I also bought two manuals and the Bernstein book, so I will be prepared as soon as I can put together the financing of the system I have in mind.