This 3 pack service kit plus water optimiser is designed with our customers in mind. It contains everything you need to complete your regular biOrb aquarium maintenance. The filter cartridge in your biOrb 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 build up from the inside surface of the biOrb and water preparation treatments 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 and 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 and complete a small water change. Also included in this pack is the biOrb Water Optimiser which improves biological filtration, removes impurities and benefits the well-being of your fish. It is 100% natural and completely safe. You can't overdose your aquarium with this fluid. Add a dose every week to help keep your aquarium crystal clear. Suitable for all aquariums. *Frequency of filter changes depends on the size of your biOrb and the fish stocking level. Please refer to your biOrb instructions for further details.