1. Rinse the water sample test tube several times with the water to be tested and then fill with sample water to the 10 ml mark.
2. Add 5 drops of reagent and gently swirl to mix, if there is an iron concentration the water changes colour. Development time is approximately 5 minutes.
3. Match the colour of the sample with the colour chart by positioning the test tube next the most similar colour. For accurate readings compare the colours from above. Caution: the iron concentration must not exceed 0,05-0,1 mg/l in freshwater and 0,05 mg/l in saltwater aquariums. Thoroughly clean the test tube after use, securely seal all reagent containers and store in a cool, dry place away from sunlight. Keep the product out of reach of children.