I think in a very large tank, that might be beneficial, but I have a small tank. The contact time with the nutrients in my fuge is very low, but because of the turn over, the contact time is constant, hmmmm. I also use a 3-4" layer of aragonite sand in my fuge, everything I've read says that the flow rate across a DSB should be very fast, hmmmm. I also do not use caulerpa, I use halimeda. I have tons of pods in the fuge, tons of pods in the tank, 0 nitrates, 0 phosphates and very little algae growth in the tank. I run alot of light on my 20, most would consider it overkill, and I over feed. I do not believe it is necessary to have a slow flow through a fuge, but in some cases it may be beneficial.