Photometric determination of free chlorine, total chlorine and ozone. • Photometric determination of free chlorine, total chlorine and ozone with N,N-diethyl-1,4-phenylene diamine (DPD)/potassium iodide. • Free chlorine, total chlorine and ozone react with DPD (N,N-diethyl-1,4-phenylene diamine) to form a red-violet dye. By defined addition of iodide ions one can differentiate between the individual components. • Type: tube test 0-17 • Range: 0.05 - 2.5 mg/l Cl2; 0.05 - 2.0 mg/l O3 • Sufficient for: 20 determinations • Sea water suitability: yes