There is a design flaw with the whisper. When you clean the filter cartridge you'll be throwing away all your benefical bacteria(BB). The filter provides no place for BB to grow, some newer models do include a foam sponge to place in front of the "biobag" cartridge.
If yours does not have this sponge, I would place a few pot scrubbies in the filterfor the BB to colonize, you can rinse these in tank water when you clean the filter. Now when you change out the cartridge you'll still have a colony of BB to biologically filter your tank.
If yours does not have this sponge, I would place a few pot scrubbies in the filterfor the BB to colonize, you can rinse these in tank water when you clean the filter. Now when you change out the cartridge you'll still have a colony of BB to biologically filter your tank.
