I have already replaced the stock pump with a MJ1200. I have the stock y with a Hydor on one end. I have tried leaving the stock y, Hydor Flo by itself, and the Hydor and duckbill together. None of them seem to give me enough flow. I have some green star polyps in mine and they don't move around much. I was thinking about putting 2 MJ900's instead, but how would I add another MJ with the aquarium full of water?