i have 2 ac110's on a 47 gallon .. and one has filter floss, bio balls and a bag of purigen.. the other has the foam block, 2 bags of the nano (little black) bio balls and a bag of ceramic ring.. that tank is really crystal clear and nitrates are around 20 so i guess its working ok.. i have the bio balls in bags sitting in the top most layer--that way they are maybe 1/2 submerged..