Circular Flow in FO/FOWLR Displays


New member
I am a strong advocate for a circular flow pattern in FO and Pond/Lagoon systems.

This came to mind when i fed today, a combination of Gulf shrimp and Chowder clams. The clams were torn to shreds and for the first time ever, i fed the shark lagoon/pond too much shrimp. Normally nothing is left behind. But back to what i was pondering. In round pools (or oval) it is very easy to create a circulating current. You aim your returns along one wall, any closed loops or flow pumps down the other and have your pump intake , not too close, but near the returns and your water comes full circle. If you see in my videos how the returns from the tanks in the adjacent room are at about a 45 degree angle, thats because i tried to replicate this flow pattern in my square lagoon.

The pump intake is in the center of the close side of the square. The LR tank's returns are in the corner of the close wall and the right wall. Theres nothing on the far wall, but this doesnt seem to matter (if you could add a pump/powerhead it would be beneficial) , and then you can see my 45 degree returns on the left wall.

Now when i fed today, and the clam pieces and cubes of shrimp were left uneaten, I thought I had a big clean up to do. But i waited a few minutes to see if any fish would finish them off. And then in the close left corner where i was standing, all of the uneaten food began to appear, slowly drifting by, towards the pump intake. All i had to do was stand there and collect the pieces as the current picked them up and drove them by me.

Anyway, this idea of circular flow is good for mechanical reasons like i said, but it also benefits your biological filtration as well. Making sure that all of the water gets a chance to be pumped through your bio media, in my case a LR tank and a Ecosystem Miracle Mud sump, is a gaurantee that your nitrifying bacteria gets a chance at consuming and precipitating ammonia and nitrite. I also have my skimmer's pump intake along that wall. On the LR tank is my biopellet reactor as well, feeding its effluent into my big skimmer. So this also gets a chance to take the precipitated nitrogenous waste and consume it (BP bacteria) or turn it into nitrogen gas (Miracle Mud).

Withholding, SPS Displays, and perhaps all Scleractinian displays, I believe this type of flow to be the optimal achievement?
Obviously hard corals need chaotic, turbulent flow to provide food and remove mucous/waste so these types of aquariums would only benefit, if in some way the circular flow was provided on the perimeter of a chaotic/turbulent flow in a centralized reef area.
What are your thoughts?