Lovibond test kits offer a lower total cost of ownership. One piece comparator design means no chance of breakage. Plus reagents and replacement color wheels are less expensive than the leading brand.
Simply fill one tube with DI water and the other with sample to the 10 mL mark. Pipet 2 mL SPADNS reagent into each cell. Insert the cells into the comparitor and match the two color fields. Results are reported as mg/L F-.