I've had good luck with moving media around the get a filter going.
Squeeze the sponge juice into the fx6 a few times and then leave some in there as well. Let it settle for 5 minutes and then when you first start up the fx6 cut the flow down to 20% for the first hour... then slowly increase the flow over the next 10 minutes or so until you are wide open. This way don't have a big rush of loose particles into the tank.