1.5 l cleaning solution for nitrate/SAK, nitrite, orthophosphate and P-total based on lye to the analysis module TresCon® ON 210 and OS 210, TresCon® ON 510, TresCon® OP 210, TresCon® OP 510, as well as the TresCon® analyzer N211/S211/N511/P211/P511 and TCU/N211/S211/N511/P211. Can also be used as ammonium reagent solution for the TresCon® OA110 analysis module and TresCon® A111 and TCU/A111 analyzers