Biorb Marine Service Kit-Oase Biorb Service Kit-Biorb Fish Tank Filter The filter cartridge in your biOrb should be changed every 4 weeks*. This is the kit you need to replace your filter cartridge and maintain your Marine biOrb. Maintaining a Marine aquarium is a little more involved than a freshwater aquarium. We have made it as simple as possible by supplying everything you need in one kit. The kit contains a replacement filter cartridge which is specifically for Marine biOrb (the biOrb Standard Service Kit should not be used in Marine biOrb as it contains a different mix of chemicals). A measured amount of high quality reef grade salt and water preparation chemicals are also supplied as well as easy to follow step by step instructions. The filter cartridge in your biOrb should be changed regularly. 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. 1 x Marine Replacement Filter Cartridge 500g High Quality reef salt 1 x Cleaning Pad 1 x Water Treatment Sachet