A couple of things:

If one scoop of powder turns the water pink, you don't have to add the second one. That will make the powder last longer.

If you are going to use the 5mL water sample, you multiply the number of drops of R0871 by 1ppm. So, 32 drops would be 32ppm of FC. (Are you sure you used 5mL water sample?)

(When using 10mL sample, multiply number of drops by 0.5. With 25 mL sample, multiply by 0.2.)