How To Block Filter & Slow Output

My fish is ruining his fins by resting against the input filter and its "sucking" his fins in. How do i fix this without effecting the filter?

Also, i think the output flow is a bit strong. How do i fix this too?

Thanks!!

 

We will need to know what kind of filter you have.

Different filters need slightly different modifications.

 

Put a pre filter over the intake.

 

I used the water bottle method to slow the output and it worked wonderful...just make sure to keep the water level below the bottle so that he can't rip his fins on the plastic.