1. Rinse the water sample test tube several times with the water to be tested and then fill with sample water to the 5 ml mark
2. Add 10 drops of the reagent contained in the bottle and gently swirl to mix. If there is a nitrite concentration the water changes colour.
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: in the event the nitrite concentration exceeds 1 mg/l it is necessary to regularly change a small quantity of the aquarium water and use a specific product such as PRODAC's NITRIDAC. 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.