For perfect aquarium plant growth: determines the ideal potassium value to monitor the fertilisation of freshwater aquariums Quick test: fill cuvette with sample water, add reagents, fill cloudy sample water into special glass vial until underlying cross is no longer visible, read the quantity you have filled. This value is equivalent to the potassium content in mg/l Often too low a potassium content leads to stagnating plant growth, although all other factors such as CO2, iron and light are present. Fertilisers such as JBL Ferropol or JBL ProScape K Macroelements can increase the K content You will find detailed information and troubleshooting tips about water analysis on the JBL website in Essentials/Aquarium Package contents: 1 potassium test kit for approx. 25 measurements, incl. 2 reagents, special glass vial, syringe, dosing spoon and colour chart. Reagent refill separately available