I just got a Fluval G3 for a new 75 G tank. I set it up as per instructions and primed it until no bubbles were coming out of the output nozzle. When I plug it in, the filter initializes and then there is one burst of water out of the output nozzle when the filter starts, then nothing. The filter sounds like it is running, but there is no water flow. I have taken it apart and inspected the impeller and it seems fine. Customer service has not been very responsive yet. Any ideas?