Sera Aqua-Test Box Marin Master Test Kit for Saltwater AquariumsOur Sera Aqua-Test Box Marin Master Test Kit for Saltwater Aquariums is a professional set that consists of nine different water tests for aquarists. This master test kit tests for pH, kH, GH, NH3/NH4, NO2, NO3, PO4, Cu, and Ca. Kit comes complete with distilled water, comparison chart, glass vials and provides access to Sera Online Backup. This free service is offered so you can evaluate the water values of your aquariums in the Sera Online Lab. Thus you are always informed about the water quality. The Sera Online Lab will give you valuable clues on how to improve them if there should be something wrong with the water values.