Monitors water values in aquariums simply and reliably. It determines pH (three ranges), carbonate hardness, general hardness, ammonium/ammonia, nitrite, nitrate, phosphate, iron, copper, silicate, oxygen, and, with the help of a table, the CO2 calculation. Add the reagents to the water samples, compare on the colour chart, read off the values, and check the analysis sheet to see which actions are recommended, if any. The comparator system takes the inherent water colouring into account. CO2 content is determined by pH value and KH value using the table. It contains a childproof reagent bottle in a waterproof plastic case. Refill reagents are separately available.