• Ensure that the test tube is clean before use.
• Clean the tube directly after use.
• Take the volume of the water sample as precisely as possible.
• Keep the dripping bottle perfectly vertical during dropping.
• Take care that no air bubbles are included in the drops.
1. Take a water sample of 20 ml.
2. Add 10 drops of PO4-1 test fluid and shake.
3. Add 2 drops of PO4-2 test fluid and shake again. PO4-2 is a thick liquid so press firmly on the bottle and then it takes a while before the drop appears.
4. Wait 10 minutes.
5. Determine the PO4 -value using the included colour chart.