A biOrb Aquarium does not require much care. However, to continuously ensure the optimal water quality, the filter - depending on fish stock - should be changed every 4 to 8 weeks. This is quite simple: Unscrew the old cartridge on the air column, replace the old filter cartridge with a new filter cartridge and then screw it back into the fixture.This pack includes three complete service kits3x filter cartridge (sealed)3x cleaning cloth3x water treatment sachetsInstructionsPlusa 100ml bottle of Water Optimiser - suitable for all biOrb aquariums