I have a 20gallon fuge and my tank is 34 gallon, I have no filter socks. This allows many forms of food to make it's way into the main tank, which is loaded with pods, as is my fuge. I find the added benefit of the opposite light cycle to balance ph, the supplemental fish and coral feedings, and the nutrient uptake by the macro algae provide the stability that I feel I would not achieve with the smaller tank I have, the sps are very happy... Not a must, but a must for me...