Sorry this took me so long. I had to leave town for a week an then have been a little busy.
I am very disappointed to say that after three consecutive tests I am not very impressed with the accuracy. I just finished the three tests and got a variety of readings: 431, 408, and 481. I followed the directions to the "T", and still did not get good results. I'm going to be getting in contact with Hanna to see if they have any suggestions. I'll definitely post here what I find out.