Ionometer analyzer (K). The first instrument was a Potas-sium (K) analyzer to measure this element in the inflow andoutflow of the constructed wetland, doing consecutive measures.This instrument is a PowerMon ionometer (Bran + Luebbe, Norder-stedt, Germany). The ionometer is a device for the potentiometricmeasurements of substances dissolved in water. K+concentrationis measured using an ion-selective electrode. The ionometer is per-manently connected to the process to be analyzed by means of