Originally Posted by Canuck Fins
On my filter, if my fish was getting fins caught in the water intake, I'd wrap one around it and elastic it in place. For some filters, it can be stuffed into the tube so water can pass through but the fish can't go in. It's also a place where good tank bacteria will hang out. Baffle=slow down the water.
For the input (depending on the type of filter, HOB) you can often use:
to reduce the intake flow. I've used it on 2 non-Fluval filters. I would be a bit cautious about stuffing anything into the input tube as I wrecked my filter by doing that. The piece got stuck too far in the pipe (ran fine for a while) and reduced the output flow to almost nothing. The piece got stuck in a spot where it couldn't be retrieved and thus the filter is no more.