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I tried ehiem 3000 , It is not drawing water from the tank when set it up outside the tank. I set it up outside the tank because it is too big for my iOS, and i ended up, set up an additional small sump inside m iOS which means I used 2 pumps for the fr. I had no problem setting up an external canister without an additional pump earlier on. Any advise bro? I read ehiem 3000 it said I need to do suction for external setup, can any bro advise how do I do that?