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March 14, 2016


Questions About Bioflocs


Cécile Mablouké (, who holds a PhD in Marine Ecology, writes:


I am currently working on a project to develop a biofloc shrimp farm in southern France.  I’ve run into a few obstacles, and I was wondering if you could help or if there was a possibility for me to reach the “flockers network” to get some information?


My first question is about settling tanks to control the amount suspended solids.  How do you size them?  I read that the water velocity was very important in helping the solids settle correctly.  For example, I read that a minimal-exchange, super-intensive system using plant-based feeds required a chamber 0.55 meters in diameter and a flow rate of six liters a minute, or 1.5 miles per hour.  Is that accurate?  Is it the only parameter that we must take into account?  Don’t we have to take the volume of the tank into consideration?


Also, I know that it’s possible to use an airlift system to aerate the tanks.  How much airflow is needed to keep the biofloc in suspension and to provide adequate oxygen for the shrimp?


Finally, I found that there were many ways to start the biofloc culture.  One of them suggests a carbon: nitrogen ratio greater than 15:1.  Another recommends inoculating the tanks with powdered shrimp feed and a source of carbon for seven weeks prior to stocking.  We were thinking about trying the second solution.  What do you think about it?


Source: Email to Shrimp News International.  Subject: A Few Questions About Biofloc.  From: Cécile Mablouké.  March 15, 2016.

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