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Hello, so yesterday my U3 fluval underwater just stopped working, I noticed because there was no water flow. I was really worried, so I went out I got a Hang on back filter from Walmart. Since it was 11pm already and all LFS were closed and I didn’t want to leave the tank overnight with no filtration. I got a tetra whisper advanced filter from Walmart that holds for 30-60 gallons. My question is what do I do with the old filter? Would I leave the old filter in my tank for a month until the beneficial bacteria establishes in my new filter? Help Please!!!!