Bens original instructions were to add DPD powder until the water turned pink. He said it could take one or two scoops. I dont think it went on to say you had to do anything with the resulting drop counts (i.e. if you used 2 scoops, did you need to take half the count of drops you used). I also dont know if how many scoops of DPD you use is related in any way to the amount of CL in your water....Ive had FC down to .5 and still only needed one scoop of DPD to get the water pink.

That might be why you noticed no difference......if the water turned pink on the first scoop, you were probably good to go.

-Chris