Comparator system 2000, water test discs and reagent tablets A large selection o water test discs are available for colorimetric chemical analyses and colour cla sification. Each test disc is equipped with fade-free, non porous glass filters, he qual ity of which is not impaired by UV light or other environmental influence . Test discs whose code begins with ''''N'''', are designed for use in the Nessleris r 2150. Test discs which start with the letter ''''C'''' are designed for use in the essleriser 225 0. All other test discs are designed for use in the comparator2000 . The most popular water test discs feature in the table below. Other testdiscs re available on request. For , Disc CAA , Measuring range 0 to 30 mgPt / l