@Elaine - my filter sponge in the new filter is not like a usual sponge
- it's more like plastic steel wool... so when I clean it most of the
brown junk comes off. If this happens, does this mean that the
bacteria are getting washed away too? I just find it hard to believe
that the new sponge will hold as much bacteria as the old one. Perhaps
I will get a better sponge and cut it to fit my new filter.