I see what you are saying. My flow THROUGH my fuge is only 2/3 of my Mag7 return pump(2 of the 3 return branches drain into the algae sump, the third, back into the main sump). The RIO 1700 under some LR pieces just jams the water in the tub around in the tub to maximize exposure to the very dense algae wad that I am able to sustain, because (IMO) of the strong flow and the strong light. I am just looking to ensure no dead spots in the algae wad which would possibly founder or die.