7 Your own measurements: Desired value Date and time Standardmeasurement pH KH (°dKH) NH4 (mg/l) NO2 (mg/l) Testasrequired GH (°dGH) NO3 (mg/l) PO4 (mg/l) Fe (mg/l) Cu (mg/l) Cl (mg/l) SiO3 (mg/l) O2 (mg/l) Others (e.g. CO2, tem- perature, conductivity)