I just bought a Fish last week from a guy with same sump. He showed me his setup. His way around was one clarisea and one 7 inch sock. You will get more flow then. The problem is when you have a large tank and you need the high turn over rate this sump can’t do it with the filter rollers. As far as user error I emailed him just as you did he had no solutions. I will post some pics give me a little bit and see for yourself