For anyone who has a Red Sea Reefer and their return flow is 450 gph or greater and experiences air getting sucked down the overflow from the vortex created inside the silencer, this modification will solve that noise problem. To solve it something should be inserted into the middle of the vortex to stop it’s creation. I added an acrylic rod to the Red Sea overflow box top which is acrylic as well, positioned right in the middle of the silencer. This solution has stopped the vortex noise from being created. Please see video.

