Available at Notcutts comes the Service Kit. This is the kit you need to replace your filter cartridge & maintain your bi Orb. The filter cartridge in your bi Orb should be changed every 4-8 weeks. A new cartridge is supplied in the Service Kit as well as a special cleaning pad for removing dirt & algae from the inside surface of the bi Orb & water preparation chemicals for carrying out a partial water change. The kit also contains easy to follow step by step instructions. Most aquariums have filters with several compartments containing different types of filter media which needs to be carefully cut, measured & changed. Changing too much or too little can result in water quality problems. In the Service Kit this has all been done for you, so you just have to replace the filter cartridge & dont need to worry. Frequency of filter changes depends on the size of your bi Orb & the fish stocking level. Please refer to your bi Orb instructions for further details. Included Items 1 x Replacement Filter Cartridge 1 x Water Preparation Chemicals 1 x Cleaning Pad Aquarium Key Features New cartridge supplied Special cleaning pad for removing dirt & algae Instructions included