When its time to change my filter media on my Hang on back filter how do i remove the floss without losing BB? I know pet product manufacturers recommend every month but most people keep it in untill it's just floss. On my 10 gallon theres little space to stuff the floss behind the new cartridge. Also when you do a water change and i move the filter cartridge a bit up or down. A lot of gunk is released into the water. How safe is it for my fish?