I am trying to design my DWCs which are relatively big. Each are 500 m² and designed in a way that fish water inlet and outlet are at the same side. Kinda like a runway system with retention time around 3 hours. Fish water reaches the end of DWC and returns back to the inlet side in the next lane.
The reason for this kind of design is converting a batch process (fish feeding) into a continuous process. Frequent and sequenced feeding of each fish tank should enable me control the concentration of nutrients at every stage of production. Of course there are mechanisms that control the nutrient intake but I am assuming they are managed accordingly.
So the question is how does a system like this effects Fish health. What may be the drawbacks of such design? Concentration along the DWC would be different then the conventional design where at the fish water inlet usually ripe produce is placed. How this would effect the system and finally is there a paper regarding concentration of nutrient change along the DWCs.
Best Regards
MMulayim
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It doesn’t work like that. You can have all of the control you want with the fish feed rate and it wont effect the nutrient diversity. Fish waste simply does not have all of the nutrients plants require even if you use some of the fancier more expensive feeds which on average are 2x or more of the cost of simply supplementing the systems properly. The economics simply doesn’t work for that and neither does the chemistry.
Design wise its doable to build a system like you ask but 3 hour turn over time is way higher than most systems which are 1 - 3 times a day on average for bigger systems.
I think your trying to pick the most complicated way to solve a simple solution.
In essence I am trying to design my system as a hybrid system which constitutes both coupled and de-coupled parts. Coupled part as described above will continuously bleed into decoupled part. The amount of nutrient rich water that is lost to the de-coupled part will be compensated as fresh water at the coupled parts Sump.
That may be over complicated as you mentioned. Easier way would be separate both systems and add additional nutrients when necessary as the industry does at the moment.
Don’t bother just make a single loop or multiloop so you can reroute it. Decoupled are useless outside of cold water fish really. They cost way more money with less over all results and control than a single or multiloop system where you reroute the tanks to different sumps but always a closed loop with the fish.
Decoupled really has no purpose any more now that we better understand how to mineralize fish waste and with hybrid planting methods its simply just an out of date design.
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The folded raceway is a Carousell design. A good place for solid removal & surface skim at the change in flow direction. Possible to pump across and maintain a channel flow. Pump can deliver through a Venturi aerator to provide DO
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