I've been using a Fluval C2 for a few months now and everything has been fine (other than the impeller noise) until recently. When I first got the filter, hardly any water was making it's way up through the spout that feeds the trickle chamber. Flow through the filter was great. Now there is substantially more flow through the trickle chamber spout and not as much through the filter. The C2 has a flow indicator that pops up when the filter begins to clog, but my indicator is not sticking up (it does work however). Does this indicator only pop up when the foam filter is clogged? Mine is clean, so the only other thing I can think of is my media (Matrix) is dirty and reducing flow and perhaps the indicator doesn't pop up when the basket gets clogged. Anyone have a Fluval C2 that can comment on this issue? Can I safely rinse the Matrix in tank wayer without disturbing the BB too much?