What is the correct method for adding Sodium Thiosulfate to cooling tower basin samples?

The method of adding Sodium Thiosulfate using a dropper bottle is correct because it allows for precise control over the volume being added to the water sample. This precision is crucial for ensuring accurate neutralization of chlorine or chloramines that may interfere with subsequent testing for microbial contaminants, including Legionella. The dropper bottle method helps to achieve the desired concentration of Sodium Thiosulfate in the sample quickly and uniformly, ensuring effective dechlorination.

Other methods, like mixing Sodium Thiosulfate directly into the cooling tower basin or utilizing pre-treated bottles, could potentially lead to inconsistent results. Adding it directly to the basin does not allow for accurate dosage determination, which could affect the sample quality. Pre-treated bottles complicate the process as they require prior preparation and careful handling to ensure they are effective without contamination. Storing the Sodium Thiosulfate in the cooling tower overnight is not practical because it may degrade or react in unexpected ways, compromising the integrity of the water sample for testing.